Lubricants and Lubrication Part 14 pot

Standard test method for wear-preventive characteristics of lubricating fluids ASTM D 4172 Wear-preventive characteristics of lubricating grease four-ball method ASTM D 2266 Standard tes

737 19.2 Simple Mechanical–Dynamic Lubricant Test Machines

Test conditions

- Normal operating conditions

- Extended operating conditions

II Test laboratory with complete

vehicle (equipment) or plant

- Close to normal operating

conditions

- Extended operating conditions

III Test laboratory with plant or

construction elements

- Normal operating conditions

- Extended operating conditions

IV Experiment with standard

construction element or

scaled down plant

equipment operating close

to normal conditions

VI Experiment with simple

laboratory test equipment

738 19 Mechanical–Dynamic Test Methods for Lubricants

tests the ball’s surface will first produce wear marks on the fixed balls which lead toeffects of different oils and additives

Fig 19.2 Schematic diagram of the test principle of the four-ball apparatus.

In recent years, several adapters have been developed for the four-ball apparatus

to furnish information on the pitting load capacity and the shear stability of mer-containing lubricants Surface-modified steel balls (VW-PV-1444) and a variety

poly-of tapered roller bearings (VW-PV-1417, DIN 51354, part 6 or CEC L-45-T-98) areused (Fig 19.3) In addition, further modifications of the test adapters enable thedetermination of friction coefficients and temperature behavior of a lubricant withinthe roller bearing In accordance with VW-PV-1454 the test adapter used determines

Fig 19.3 Test adapter for determination of the shear stability of lubricants containing polymers.

739 19.2 Simple Mechanical–Dynamic Lubricant Test Machinesthe steady-state operating temperature, temperature increase, and the friction of thetest bearing in relation to the respective lubricant, using a axial thrust ball bearing.More recent results with this test adapter have shown that the steady-state oil sumptemperatures measured can be transferred to transmissions and industrial gears,depending on the lubricant, after being adjusted to the realistic load and speed ratioreferring to the application As ever, today’s numerous specifications for gear andhydraulic lubrication oils and for all types of grease and paste require four-ball datafor most of the lubricants Table 19.1 lists the common test standards mostly usedfor the four-ball apparatus.

Tab 19.1 Four-ball apparatus test standards.

Standard test method for wear-preventive characteristics of lubricating

fluids

ASTM D 4172

Wear-preventive characteristics of lubricating grease (four-ball method) ASTM D 2266

Standard test method for the determination of the friction coefficient of

lubricants using the four-ball apparatus

ASTM D 5183

Measurement of extreme pressure properties of lubricating fluids

(four-ball method)

ASTM D 2783 Measurement of extreme pressure properties of lubricating grease

(four-ball method)

ASTM D 2596

Standard test method for determination of load-carrying capacity and

mean Hertz load

FTMS No 791 b Method 6503.2 Determination of extreme pressure and anti-wear properties of lubricants

– four-ball apparatus

IP 239/85

Standard test method for lubricants using the Shell four-ball apparatus

General working principles

Weld load of liquid lubricants

Wear load of liquid lubricants

Weld load of solid lubricants

Wear load of solid lubricants

Shear stability of polymer-containing lubricants

DIN 51350 DIN 51350, Part 1 DIN 51350, Part 2 DIN 51350, Part 3 DIN 51350, Part 4 DIN 51350, Part 5 DIN 51350, Part 6 Viscosity shear stability of transmission lubricants – tapered roller

bearing

CEC L-45-T-98

Mechanical shear stability of engine oils VW-PV-1450

Pitting load capacity of solid lubricants VW-PV-1417

Pitting load capacity of liquid lubricants VW-PV-1444

Standard test method for temperature increase in the axial thrust ball

bearing adapter (ARKL)

VW-PV-1454

740 19 Mechanical–Dynamic Test Methods for Lubricants

19.2.2

Reichert’s Friction-wear Balance, Brugger Apparatus

The Reichert’s friction-wear balance and the Brugger apparatus (according to DIN50347) are important tools for determination of the wear characteristics of water-containing and nonwater-containing metal-working fluids, hydraulic fluids, andgreases Most manufactures in the metal-working industry specify wear-data accord-ing to Reichert or Brugger to ensure an adequate quality standard and adequatequality control for their metal-working and hydraulic fluids Almost each develop-ment of a new formulation includes these wear tests By means of a lever-handlesystem a firmly clamped cylindrical roller is pressed axial-crossed against a slip ring

by an applied normal force (normal load) The slip ring rotates cross-directionally tothe roller In accordance with to Reichert approximately the lower third of the testring is dipped into the test fluid After a walkway of 100 m at a constant speed of therotating slip ring, the elliptical wear mark produced on the roller’s surface is mea-sured According to Brugger the slip ring rotates for 30 s with 5 mL fluid lubricatingthe friction contact The fluid must remain on the surface for the duration of theBrugger test

On the basis of the wear marks measured, the average specific contact pressurecan be re-calculated from the known and constant normal force The wear is a result

of the wear rate The Reichert friction-wear balance and the Brugger apparatusequalize the contact pressure by producing smaller or larger wear marks Figure19.4 shows a schematic diagram of the test arrangement and Fig 19.5 gives exam-ples of wear marks measured with the Reichert friction-wear balance Common teststandards are listed in Table 19.2

Normal force

Roller Ring

Fig 19.4 Schematic diagram of Reichert’s friction-wear balance.

741 19.2 Simple Mechanical–Dynamic Lubricant Test Machines

Fig 19.5 Examples of wear marks determined in accordance with Reichert: A canned milk; B cola.

Tab 19.2 Reichert and Brugger test standards.

Reichert’s

friction-wear balance

Standard test method for determining the pressure compensation capacity using the frictional wear-balance according to Reichert

VKIS – worksheet No 6

Brugger rig Testing under boundary lubricating

conditions using the Brugger apparatus General working principles

Procedures for greases

DIN 51347

DIN 51347, Part 1 DIN 51347, Part 219.2.3

Falex Test Machines

Falex test machines are mostly standardized by ASTM They are used for testinglubrication oils, greases and solids World-wide these test machines are widely used

to measure and evaluate the properties of lubricants

19.2.3.1 Falex Block-on-ring Test Machine

The Falex block-on-ring test machine is used as a development and quality-controlinstrument for simulation of sliding and oscillating wear between lubricated anddry conditions The pressure chamber and heater cover enable testing at elevatedtemperature and in noncorrosive gases Test geometry consists of a rectangular testblock that is loaded on a rotating or oscillating ring A uniform contact velocity pro-file is created The block can be replaced by a ball (increase contact pressure) or con-forming block (reduce pressure) Test blocks can be machined to test a wide variety

of products The test machine has a variable test load (<4000 N) and speed(<3000 rpm) A heated test chamber (150 C; higher if special seals are used), a highpressure test chamber (<10 bar) for noncorrosive gases or regulation of humidity,and on-line measurement of friction, temperatures, and total wear are additionalfeatures The test standards are listed in Table 19.3

742 19 Mechanical–Dynamic Test Methods for Lubricants

Tab 19.3 ASTM test standards for Falex machines.

Falex block-on-ring Calibration and operation of the Falex

block-on-ring friction and wear-testing machine

ASTM D 2714

Wear life of solid-film lubricants in oscillating motion

ASTM D 2981 Test method for wear-preventive properties of

lubricating greases using the (Falex) block-on-ring machine in oscillating motion

Endurance (wear) life and load carrying capacity

of solid film lubricants

ASTM D 2625 Method for measuring wear properties of fluid

lubricants (Falex method)

19.2.3.2 The Falex Pin and Vee Block Test Machine

The Falex pin and vee block test machine is the oldest industrially standardized tion and wear-test machine A rotating journal pin is pressed between two blockswith V-notches At constant rotational speed the normal force is increased stepwise.The scuffing load is determined at the point at which the pin at a softer neck breaks

fric-at the designfric-ated breaking point If a lubricant withstands the applied force, thewear-loss of the softer pin is measured This test is conducted at ambient tempera-ture Figure 19.6 shows a schematic diagram of the test arrangement and the teststandards are listed in Table 19.3 This test runs at fixed speeds enabling loads up to

3000 lb (13 350 N) for different test materials while controlling on-line wear, tion, load, and temperatures via the monitoring system

fric-743 19.2 Simple Mechanical–Dynamic Lubricant Test Machines

Fig 19.6 Schematic diagram of the Falex pin and vee block test machine.

19.2.3.3 Falex High-performance Multispecimen Test Machine

The Falex high-performance multispecimen test machine is extremely flexible testequipment for industrial simulations The Multispecimen machine can be used foralmost any tribological investigation that involves sliding or rolling contacts Over

60 standard adapters are available for performing a variety of simulation tests cluding sliding wear, abrasion, erosion, forming, impact, and rolling/sliding Thistest machine enables any combinations of high load (<10 000 N), high speed(<10 000 rpm), and high temperature testing (up to 800 C) The PC-controlledmonitoring system enables programming of acceleration (1000 rpm s-1) and loadingprofiles (1000 N s-1) Automatic simulation of dynamic conditions and start–stopcycles, variable flexibility enabling simulation of the effects of low-component stiff-ness, and on-line measurement of friction, speed, load, and temperature are currentstandards The test standards used worldwide are listed in Table 19.3

in-19.2.3.4 Falex Tapping Torque Test Machine

The Falex tapping torque test machine was developed to enable repeatable and cise characterization of cutting lubricants A Procunier tapping head performs tap-ping operations and a load cell monitors torque produced on a nut blank The effi-

pre-744 19 Mechanical–Dynamic Test Methods for Lubricants

ciency of cutting fluids can be determined in accordance with ASTM D 5619(Table 19.3) Tapping simulation by tapping operation in standardized nut blanks(aluminum, steel, and stainless steel), drilling, reaming and forming simulationsare possible with this test machine A roll-forming adapter characterizes rollingfluids It has a dual speed range (10–450/20–900 rpm) and a data-acquisition systemenabling torque trace and torque averages to be stored Average torque values areplotted and compared with a reference to determine the efficiency of the fluid.19.2.4

Timken Test Machine

The Timken test machine is licensed by the company Timken, a steel-producer andbearing manufacturer It is essentially used to determine the anti-scoring protectionafforded by greases and oils, in accordance with ASTM D 2509 and D 2782 It canalso be used to determine wear resistance or adhesion strength of coatings support-ing variable speed and pneumatic loading Figure 19.7 shows a schematic diagram

of the test arrangement In the steel industry the Timken rig is still a very importanttool Gear oils and extreme-pressure greases for roller bearings used in these indus-tries must meet Timken specifications The lubricant test is conducted in a frictionarrangement comprising a cuboid-arranged block and a rotating test cup (Fig 19.7).The test is run with a lubrication oil circulation system, which can be adjusted vari-ably, and with a grease feeder with a feed volume of 45 g min-1 The normal force(load stage), which is increased gradually, is brought into friction contact via the testblock Weighing of the test block and the test cup enables the determination of thewear-loss The duration of the test at each load stage is 10 min at a speed of

800 rpm

Scuffing between the test cup and the test block depends on the applied normal forceand will, first, lead to score marks on the surfaces of the test pieces Scuffing is con-nected with a sudden drop in rotational speed and/or with an increased noise level Ifscuffing occurs during a load stage, a nonscuffing test run in the previous load stagemust be proven and documented as the determined so-called “good-load-stage”

Fig 19.7 Schematic diagram of the Timken test machine.

745 19.2 Simple Mechanical–Dynamic Lubricant Test Machinestogether with the total wear of the test block and test cup (test ring) Greases aretested at ambient temperature, lubrication oils at 40 C The test standards are listed

in Table 19.4 Timken specifies an EP lubricant for bearing applications as one with

a good-load of 45 lb (200 N) To meet the requirement of anti-wear, the steel try usually defines a maximum of 5 to 6 mg at a good-load-stage of 40 lb (178 N).Higher good-loads will very often lead to greater wear

indus-Tab 19.4 Test standards for Timken machines.

Measurement of load-carrying capacity of lubricating grease

(Timken)

ASTM D 2509

IP 326/83 Measurement of extreme-pressure properties of lubricating fluids

(Timken)

ASTM D 2782

IP 240/92 Standard test method in the mixed-lubrication regime using the

Timken test machine

General working principles

Procedures for lubricating oils

Procedures for lubricating greases

E-DIN 51434

E-DIN 51434, Part 1 E-DIN 51434, Part 2 E-DIN 51434, Part 3 Standard test method for liquid and plastic lubricants using the

Timken test machine

VDEh SEB 181302

19.2.5

High-frequency Reciprocating Test Machines

19.2.5.1 High-frequency Reciprocating Rig (HFRR)

The HFRR is a microprocessor-controlled reciprocating friction and wear test systemwhich enables rapid, repeatable assessment of the performance of fuels and lubri-cants It is particularly suitable for wear-testing relatively poor lubricants, for exam-ple diesel fuels, and for boundary friction measurements of engine oils, greases,and other compounds The HFRR test for diesel fuel lubricity gained CEC “A’’(approval) status in September 1996 after an extensive round-robin program Otherstandards based on the HFRR system are listed in Table 19.5

746 19 Mechanical–Dynamic Test Methods for Lubricants

Tab 19.5 Test standards for high-frequency reciprocating test machines.

HFRR Measurement of diesel fuel lubricity CEC F-06-A-96

Standard test method for evaluating the lubricity

of diesel fuels by use of the frequency reciprocating rig (HFRR)

high-ASTM D 6079

Assessment of lubricity by use of the frequency reciprocating rig (HFRR) Part 1 test method

ASTM D 5707

Tribological test method using a high-frequency, linear-oscillation test machine (SRV); general working principles

Determination of measured friction and wear quantities for lubricating oils

Determination of the tribological behavior of materials in reaction with lubricants Definition of data formats for test results Tribological test method for solids using a high- frequency, linear-oscillation test machine (SRV)

DIN 51834

DIN 51834, Part 1

DIN 51834, Part 2

DIN 51834, Part 3 DIN 51834, Part 5 DIN 51834, Part 6

Textile machinery and accessories – needle and sinker lubricating oils for weft knitting indepen- dent needle machines – part 2

Minimum requirements synthetic oil based

DIN 62136, Part 2

19.2.5.2 High-frequency, Linear-oscillation Test Machine (SRV)

The high-frequency, linear-oscillation test machine (SRV) is designed to simulatevery small displacements under well known conditions of load, speed, and environ-mental control It is used to investigate typical fretting phenomena occurring inautomotive components, aircraft, and vibrating machines The effects of humidityand operating conditions on the surface degradation of coatings and materials can

be tested on such a machine

747 19.2 Simple Mechanical–Dynamic Lubricant Test Machines

Cylinder / disc

( pH = 50 – 800 MPa )

Ball / disc ( pH = 500 – 5000 MPa )

Ring / disc ( pH = 0.25 – 20 MPa )

Test set-up

Heater ( < 280°C )

Test contact Normal force ( < 2000 N )

Reciprocating drive

( 20 – 100 Hz )

Stroke amplitude

( < 4 mm )

Fig 19.8 High-frequency, linear-oscillation test machine (SRV).

Test methods cover procedures for determining the extreme-pressure properties

of lubricating fluid and greases in high-frequency, linear-oscillation motion Furthertest methods cover procedures for determining the coefficient of friction of a lubri-cating oil or grease and its ability to protect against wear when subjected to high-frequency, linear-oscillation motion at a test load of 200 N, frequency of 50 Hz,stroke amplitude of 1.0 mm, duration of 2 h, and temperature within the range ofthe test machine, specifically, ambient to 280 C Other test loads (10 to 1200 N formodel SRV-I, 10 to 1400 N for model SRV-II, and 10 to 2000 N for model SRV-III),frequencies (5 to 500 Hz) and stroke amplitudes (0.1 to 4.0 mm) can be varied ifspecified The precision of this test method depends on the conditions stated and ontest temperature (50 or 80 C) Average wear scar dimensions on ball and coefficient

of friction are determined and reported Further test modes are linear reciprocationtesting scuffing under variable humidity using electrical contact measurements bynormal load variations or surface fatigue evaluation Figure 19.8 shows a schematicdiagram of the test arrangement and important test standards are listed inTable 19.5 A big advantage of using the SRV machine is the possibility of simplyand quickly performing systematic property studies, which require only small quan-tities of lubricant Measurement of properties different from those of the test stand-ards will, however, require sufficient experience with this test machine and withinterpretation of the test results

19.2.5.3 Mini Traction Machine (MTM)

The MTM is a computer-controlled, precision traction-measurement instrumentwhich enables fully automated traction mapping of lubricants and other fluids Themachine simulates the lubrication regime found in nonconforming components

748 19 Mechanical–Dynamic Test Methods for Lubricants

such as cams, valve trains, gears, and rolling element bearings The test contact isformed between a polished three-quarter-inch ball and a 46-mm diameter disk, eachindependently driven to produce a sliding/rolling contact To perform a test a smallsample of fluid is placed in the test reservoir and the system steps through a series

of loads, speeds, slide/roll ratios and temperatures following any one of severalstandard test programs or a custom program defined by the operator Typically, acomplete series of traction and Stribeck curves at five different temperatures up to

150 C can be generated, guaranteeing repeatable test results The MTM system vides a rapid way of evaluating the performance of new formulations of tractionfluids at the development stage The instrument has been designed so that high con-tact pressures, temperatures, and speeds can be achieved by means of a safe, com-pact, bench mountable system It is an important development tool for lubricants,although no standardized test methods are available

pro-19.2.6

Low-velocity Friction Apparatus (LVFA), Tribometer

The General Motors low-velocity friction apparatus (LVFA) was designed in the teen-sixties and has proved to enable very repeatable evaluation of friction–velocitycharacteristics at low sliding velocities [19.2, 19.3] The LVFA uses a small-scaleannular part manufactured from the original friction material from wet clutch, wetbrake, or torque converter application, running against a steel counterpart TheLVFA uses a flywheel coast-down to evaluate a full range of sliding speeds The nor-mal load is applied by deadweights through a lever at the bottom of the apparatus.The variable-speed friction tester (VSFT) [19.4, 19.5] and the l-v-Tester [19.6, 19.7]are modified versions of the LVFA The tribometer test used in Europe is also verysimilar to the LVFA [19.8, 19.9]

nine-19.2.7

Diesel Injector Apparatus

The diesel injector apparatus enables evaluation of the shear stability of containing fluids The test methods measure the viscosity loss (%) of polymer-con-taining fluids when evaluated by a diesel injector apparatus procedure that uses Eur-opean diesel injector test equipment The viscosity loss reflects polymer degradation

polymer-by shear at the nozzle This test apparatus itself is defined polymer-by a CEC L-14-A-93 dure The ASTM test methods differ from CEC-L-14-A-93 in the period of timerequired for calibration For a specified number of cycles, a sample (170 mL) oflubricant is subjected to a shear stability test in the apparatus Before and after theshear stress the kinematic viscosity is determined at 40 C for hydraulic fluids and

proce-at 100 C for crankcase oils The shear stability is defined by the relproce-ative viscositydrop According to DIN 51382, the number of cycles is 30 for crankcase oils and 250cycles for hydraulic fluids According to ASTM, viscosity loss is evaluated after both

30 and 90 cycles of shearing The ASTM D 2603 sonic shear test (Table 19.17) hasbeen used for similar evaluation of shear stability Limitations are as indicated in the

749 19.3 Performance Tests for Gear Oil Applicationssignificance statement No detailed attempt has been undertaken to correlate thetest results of the diesel injector apparatus with those of the sonic shear test method.The ASTM D 5275 test method also shears oils in a diesel injector apparatus butmay give different results, as itemized in Table 19.6.

Tab 19.6 Test standards for the diesel-injector apparatus.

Evaluation of the mechanical shear stability of lubricating oils containing

polymers (fuel injection pump)

CEC L-14-A-93

Test method for fuel-injector shear stability test (FISST) for

polymer-containing fluids

ASTM D 5275 Standard test method for shear stability of polymer-containing fluids

using a European diesel injector apparatus

ASTM D 6278

Standard test method for shear stability of polymer-containing fluids

using a European diesel injector apparatus at 30 and 90 cycles

ASTM D 7109

Determination of the shear stability of polymer-containing oils –

diesel injector rig method

IP 294/83

Determination of the shear stability of polymer-containing oils DIN 51382

19.3

Performance Tests for Gear Oil Applications

The Erdco universal test rig and the IAE gear machine are older test rigs specifiedfor performance tests of gear oils The Ryder gear-test rig is used to obtain a scuffing

or load-capacity rating for aviation oils The load capacity rating is derived fromscuffing criteria only Scuffing is one of several surface-deterioration mechanismsaffecting the life and durability of aircraft bearings and gear hardware As a result ofits use for many years as a qualification test, the Ryder gear-test method hasacquired a large database The US Navy has supported efforts to provide Ryder-likeload capacity data for gas turbine and gearbox oils These efforts also expand thescope of oil characterization beyond the perspective of a pass/fail or ranking of oils,with scuffing performance as the only criterion

To provide continuity between Ryder gear load capacity data and current or futureoil-characterization methods, this test method ranks oils with regard to a scuffingfailure event The new gear-oil test methods characterize oils with regard to traction(friction, gear efficiency) behavior The introduction of high thermal stability (HTS)oils and, particularly, corrosion-inhibited (CI) oils, has emphasized the need forgreater testing sensitivity for oils with lower than average lubricating performance.Low lubricating performance, as measured by the Ryder test, is apparent as a super-ficial form of scuffing (“micro-scuffing’’) Other gear failures that must be coveredwith the new test methods are fatigue life (“pitting’’) and superficial pitting (“micro-pitting’’) For these reasons the FZG Gear-test rig has been further improved bymuch development work and many research projects led to improvement Much ofthis research was performed by the FVA and by the Institute for Machine Elements

750 19 Mechanical–Dynamic Test Methods for Lubricants

and Gear Research Center (FZG, Munich, Germany) The FZG gear-test rig is rently widespread and the most widely accepted of application-related gear-oil tests.Gear-oil tests are specified by the Coordinating Research Council (CRC) and by theCoordinating European Council (CEC), which are nonprofit organizations thatdirect, by committee action, engineering and environmental studies on the interac-tion between automotive equipment and petroleum products Sustaining members

cur-of CRC are the American Petroleum Institute (API), the Society cur-of Automotive neers (SAE) and automobile manufacturers (General Motors, Ford, DaimlerChrys-ler, Honda, Toyota, and Volkswagen) The CEC is an industry-based organizationdeveloping new test procedures for performance testing of automotive engine oil,fuels, and transmission fluids The CEC represents the automotive fuels, lubricants,additives, and allied industries in the development of performance tests, usually viathe European industries ACEA, ATIEL, ATC, and CONCAWE

Engi-19.3.1

FZG Gear-test Rig

The FZG gear-test rig is specified in DIN 51354 part 1 [19.10] Figure 19.9 shows aschematic diagram of the FZG gear-test rig The FZG rig is a test machine with amechanical power circuit The drive gearbox and the test gearbox (slave gearbox) areconnected by two torque shafts, by friction On one shaft is a clutch to apply theload The temperature in both gearboxes can be set and controlled The test rig isdriven by an electric motor with a variable speed, usually 1500 rpm The speed can

be adjusted from 7.5 to 3000 rpm in two directions of rotation The load can either

be applied either by use of a weight system or with the tension ratchet

Fig 19.9 Schematic diagram of the FZG gear-test rig.

19.3.1.1 FZG EP Tests – Scuffing

With the lubricant to be tested specific gear teeth (A-type) run at a constant speedwith a pitch line velocity of 8.3 m s-1 (1500 rpm) and with an established initiallubricant temperature of 90 C The test gears of type A used in this test have beenadjusted to a shape which is particularly scuffing-sensitive The FZG test method

751 19.3 Performance Tests for Gear Oil ApplicationsA/8.3/90 for lubrication oils has been standardized world-wide by ISO, ASTM, IP,CEC and DIN (Table 19.7) The stress on the tooth flanks may be increased gradu-ally After completion of the test run, or after each load stage if testing in gradualsteps (gravimetric method), changes on the tooth flank surfaces (flank damage, scor-ing) are recorded by description, photographs, tooth surface roughness measure-ments, or contrast print Changes in weight of the test wheels may also be deter-mined These test results can be transferred to other gears and even play a role inthe design and calculation of gears according to DIN 3990 [19.11] Further proce-dures, for example A/16.6/90 and A/16.6/140, are also used as variations whichhave not yet been standardized.

Tab 19.7 Test standards for gear and axle oil.

Erdco universal test rig Standard test method for load-carrying

capacity of petroleum oil and synthetic fluid gear lubricants

ASTM D 1947 (FTMS No 791 B method 6512) a)

Ryder gear-test rig Load-carrying capacity of lubricating oils

Ryder gear machine

FTMS No 791 C method 6508.2 a)

IAE gear machine Determination of the load-carrying capacity

of lubricants – IAE gear machine method

IP 166/77 a)

FZG EP gear-test rig Standard test method for lubricants using

the FZG gear-test rig General working principles Standard test method A/8.3/90 for lubricating oils

DIN 51354

DIN 51354, part 1 DIN 51354, part 2

Standard test method A/2.8/50 for greases DIN technical

report 74 Load-carrying capacity test for transmission

FVA information sheet no 243/5 rev.

FZG scuffing load-carrying capacity test for high-EP oils

CEC L-84-A-02

FZG step load test A10/16.6R/120 for relative scuffing load-carrying capacity of high-EP oils

ISO 14635-2:2004

752 19 Mechanical–Dynamic Test Methods for Lubricants

FZG wear gear-test rig Standard test method for evaluating the

wear characteristics of tractor hydraulic fluids

ASTM D 4998

Method to assess the wear characteristics

of lubricants – FZG test method C/0.05/90:120/10

FVA information sheet no 54/I-IV

DGMK-FZG micro-pitting short test C/8.3/90

GFKT-DGMK-FVA project no 259/4 FZG pitting gear-test

development of a practice-relevant pitting test

FVA information sheet no 2/IV

FVA information sheet no 345/1 Comparison of gear efficiency test methods

between VW-PV-1456 and FVA info sheet 345

FVA worksheet

no 345/3 Standard test method for testing the effect

on efficiency of gear lubrication oils –

VW gear set

VW-PV-1456

Ecotrans method – assessment of the ability

of lubricants to reduce friction losses in transmission

GFC T 014 T 85

FZG gear-test rig with

oil loop for the

synthetic oil ageing

procedure

Simulation of fill-for-life lubrication using the FZG gear-test rig oil ageing procedure (test described in Refs [19.13] and [19.14])

FVA worksheet

no 357

DANA model 30 L-33-1 moisture corrosion test CRC L-33

ASTM D 6121 L-42 high-speed axle test CRC L-42 L-60 model two steel

spur gear

L-60-1 thermal and oxidative stability test CRC L-60

ASTM D 5704 Vanguard phase I Performance of hypoid oils – high torque IP 232/69 (2001)a)High speed track Hypoid oils in axles – Mira high-speed shock IP 234/69 (2001) a)

a) Obsolete but still in use

Tab 19.7 Continued.

753 19.3 Performance Tests for Gear Oil Applications19.3.1.2 FZG High-EP Tests – Scuffing Load Capacity

Oils with a large additive content, so-called high EP gear oils, for example hyoid gearoils, withstand the standard FZG test procedure for lubricating oils FVA informa-tion sheet no 243/5 rev and CEC test method L-84-A-02 describe mechanical testprocedures for lubricating oils, primarily for use in highly-loaded gear systems withand without hypoid offsets Three procedures have been defined in detail by theFVA [19.15]:

. the load stage test – procedure A10/16.6R/90,

. the shock test – procedure S-A10/16.6R/90, and

. the shock test at increased oil temperature – procedure S-A10/16.6R/110

All tests are run under enhanced operating conditions The rig is driven by anelectric motor running at double speed of 2880 rpm driving the gear wheel shaft.The direction of the drive is the reverse of that of the standard test method A/8.3/90giving a corresponding pitch line velocity of 16.6 m s-1with a driving wheel (16.6R).Further aggravating test conditions are use of A-type test gears with a pinion facewidth of 10 mm (A10) and a required starting temperature of 90 or 110 C in the oilsump (/90 or /110) and visual assessment stipulated for these procedures

The test S-A10/16.6R/110 (shock test) can be used as a screening test for the CRCL-42 test [19.12] To evaluate the oil’s load-carrying capacity for API GL 5 it is neces-sary to compare the results for the candidate oil with the results from ASTM ref-erence oil no 114-1 The ASTM reference oils can clearly be separated by approxi-mately 1.5 load stages The pass reference oil no 114-1 does not fail (LS > 10); failreference oil no 112-2 fails 100 % at load stage 9 Candidate oils meet or exceed thescuffing requirement of API GL 5 when the scuffing load stage is higher than that

of ASTM reference oil no 114-1

19.3.1.3 FZG Pitting Tests

Pitting is a form of fatigue failure which occurs on sliding rolling contact surfaces.Lubricants consisting of base oil and additives affect the pitting load capacity ofgears The method of calculation of pitting load capacity according to DIN

3990 [19.11] considers, with the flank roughness and the tangential velocity, only thekinematic viscosity of the lubricant as a lubrication-relevant affecting condition Theactual performance of the lubricant with regard to the pitting load capacity can beexperimentally determined by the “pitting test’’ method [19.16] For automotive ap-plications load-spectrum testing is possible at low (PT C/LLS/90) and high (PT C/HLS/90) loads specified by Ref [19.17] The “practice relevant pitting test’’ hasproved to be an appropriate method for testing pitting load capacity with regard topractical relevance, test duration, and reproducibility of the results [19.18] Depend-ing on the application profile the test method is defined as a single-stage test (forlubricant developers) and as an extended application test (for lubricant users) It isrecommended that helical gears are mounted in the slave gearbox Lubrication isimplemented as temperature-controlled splash lubrication Every test run is per-formed with fresh oil with the oil level at the middle of the shafts Gears of type C-PTX are specified in Ref [19.19] These gears are manufactured by ZF Friedrichsha-

754 19 Mechanical–Dynamic Test Methods for Lubricants

fen in a large production batch within the specified tolerances The results of thetest procedures require at least three or more tests under identical conditions todetermine a 50 % failure probability of fatigue life using Weibull statistics [19.20].Two procedures have been defined in detail by the FVA

. pitting test PTX C/10/90 – single stage test, load stage 10 at an oil sump perature of 90 C

tem-. pitting test PTX C/SNC/90 – application test as an extension of the singlestage test PTX C/10/90 with additional test runs of the lubricant at load stage

9 or load stage 11 depending on the result of the previous stage test; the oilsump temperature is 90 C

For special tests at different temperatures the test designations for both proceduresare modified appropriately

19.3.1.4 FZG Micro-Pitting Tests

Use of high-performance gearbox lubricants with EP additives dramatically reducesscuffing wear in gears but some of these additives increase the likelihood of micro-pitting Micro-pitting or “grey staining’’ is increasingly being observed by industry

in surface hardened (case carburized) gears Micro-pitting cracks usually grow onplanes inclined to the surface plane at angles typically between 30 and 70,depending on the position of the micro-pitting on the gear tooth, details of the lubri-cation, and gear design After some growth (5–10 mm for micro-pitting, much larg-

er for macro-pitting) the crack plane is found to be parallel to the surface In thepast there was a tendency to regard it as a secondary wear problem and much moreattention was focused on more macroscopic pitting which occurs as a result of con-tact fatigue The introduction of modern clean steels in engineering applicationsand the use of more highly formulated lubricants to prevent scuffing changed thisview, however

The FVA–FZG micro-pitting test is well established as the standard test methodGF-C/9(10)/8.3/90 (FVA information sheet no 54/I–IV) for evaluating the micro-pit-ting characteristics of lubricants used in gear drives [19.21] The FZG micro-pittingtest consists of two parts – a load-stage test then an endurance test In the load-stagetest the ability of the gear–lubricant tribological system to resist micro-pitting isdetermined under specified operating conditions (lubricant temperature, circumfer-ential speed) in the form of a failure load stage The endurance test provides infor-mation about the progress of the damage after a large number of load cycles Thistest is conducted at relatively high loads (load stages 5 to 10) In this test gears

(C-GF-type) with special surface roughness (Ra ‡ € 0.5 lm) are used [19.22] This

greater surface roughness facilitates the formation of micro-pitting on the testgears [19.23] This test method provides precise results but at relatively high costand is quite time-consuming (up to 520 h)

This FVA–FZG micro-pitting test has been supplemented by a standardizedshort-test method that enables classification of candidate lubricants in a manneranalogous to the FVA–FZG micro-pitting test [19.24] Within the scope of theresearch project (FVA no 259/4) the DGMK-FZG micro-pitting short test

755 19.3 Performance Tests for Gear Oil ApplicationsGFKT-C/8.3/90 was developed and tested with lubricants whose classification in thestandard FVA–FZG micro-pitting test is well known The new DGMK-FZG micro-pitting short test categorizes candidate lubricants into classes of micro-pitting loadcapacity analogous to the FVA–FZG micro-pitting test These classes correlate wellwith the classes of the FVA–FZG micro-pitting test The correlation between theaverage maximum profile deviation after running the DGMK-FZG micro-pittingshort test and the failure-load stage of the FVA–FZG micro-pitting test is good TheDGMK-FZG micro-pitting short test is thus regarded as a standardized short-testmethod suitable for differentiation of the micro-pitting load capacity of differentcandidate lubricants.

19.3.1.5 FZG Wear Tests

For maximum energy savings low-viscosity lubricants are frequently used Greatertransmitted power leads to higher temperatures and thus thinner lubricating films.These tendencies increase the probability of failure in gear contacts at low speeds,because of wear New test methods on modified FZG gear-test rigs have been devel-oped to evaluate the load-carrying capacity of gear lubricants For low-speed condi-tions a wear test using C-type gears at low pitch line velocity of 0.05 m s-1(7.5 rpm)and two different temperatures, 90 and 120 C, has been developed and applied tomany different lubricants to assess response to different additives at high loading ofload stage 12 (C/0.05/90:120/12; DGMK project no 377-1; Table 19.8 andRef [19.25]) Under such conditions the lubricant’s wear-protective additives are ofparticular importance

Tab 19.8 FZG/DGMK project no 377-1 wear load capacity test.

Test procedure of the FZG/DGMK wear load capacity test

Weight loss Test conditions Duration Load cycles on the test wheel

1st test stage C/0.05/90/12 2  24 h 2  12 500

2nd test stage C/0.05/120/12 2  24 h 2  12 500

3rd test stage C/0.05/90/12

C/0.57/90/12 C/0.05/120/12

1  48 h 1  25 000

1  250 000

1  25 000Test procedure of the shortened FZG/DGMK wear load capacity test

Weight loss Test conditions Duration Load cycles on the test wheel

1st test stage C/0.05/90/12 2  20 h 2  10 400

2nd test stage C/0.57/90/12 1  20 h 120 000

3rd test stage C/0.57/120/12 1  20 h 120 000

756 19 Mechanical–Dynamic Test Methods for Lubricants

The test method according to ASTM D 4998 also facilitates identification of thewear-protective capacity of lubricants, by use of the FZG gear-test rig Test methodA/0.57/120/10 is also known as the Chevron test The pitch line velocity is0.57 m s–1 (150 rpm) using A-type gears instead of C-type These wear-intensiveoperational conditions have been developed to examine the long-term wear-protec-tion capacity of universal gear-lubrication oils for tractors (UTTO) By modification

of the ASTM test method mentioned above, this method has been extended to 60 hduration as a more precise test of vehicle, industrial, and hydraulic oils As a result

of gravimetric determination of the weight loss of the test gear set after 20, 40, and60h, the running-in and long-term wear of lubrication oils can be assessed satisfac-torily

19.3.1.6 FZG Gear-efficiency Tests

The major targets of transmission design today are higher efficiency, higher torquecapacity, and reduced size Increasingly smaller transmissions with higher torquelead to higher operating temperatures The friction in the transmission is responsi-ble for temperature increase and efficiency losses, and reducing friction is the mainmeans of improving efficiency and keeping the operating temperature low Themain features of transmission design to increase efficiency are reduction of friction

of the bearings and the rotary shaft seals, reduction of sliding of the gear flanks, andreduction of splashing and pumping of the lubricant Losses in a gear system areclassified as load-dependent and speed-dependent losses, for example churning orsealing losses To identify and compare the effects of lubricants on gear efficiencytest method VW-PV-1454 (Table 19.1) [19.26], using a modified four-ball apparatusadapter, and test method VW-PV-1456 [19.27–19.29], using a modified FZG gear-testrig, have proven successful for lubricating oils and additives

All FZG test methods measure and compare the torque loss which the drivingmotor imports into the mechanical power circuit to sustain the rotational movementduring the operating conditions Another torque meter must be installed behind theinput shaft of the driving motor The same gear-set types are used in the slave gear-box and the test gearbox for these tests, and both gear boxes are filled with the sameoil at an identical level By use of this method the total losses in the no-load and loadmodes of operation are measured to determine their dependence on gear type, oiland additive formulation, viscosity grade, oil filling level, rotational speed, and load.Both test gears have, furthermore, been equipped with an adjustable heating systemwhich maintain equal oil sump temperature in each gearbox [19.30, 19.31]

The advantage of the above-mentioned procedure, in comparison with the olderso-called Ecotrans test method (GFC-T-014-T-85) [19.32], is more precise measure-ment of torque loss when using a torque meter In the Ecotrans test method thefriction torque in the mechanical power circuit is calculated by measurement of theelectrical input power of the driving motor The rotational speed and load-dependentpower input of the often different systems of electrical power input lead to signifi-cant inaccuracies, however An excellent comparison of the common FZG gear-effi-ciency methods currently in use is available elsewhere [19.31]

757 19.3 Performance Tests for Gear Oil Applications19.3.1.7 FZG Synthetic Oil Ageing Tests

Oil ageing of lubricants can be simulated in a modified FZG back-to-back gear-testrig [19.33] A schematic diagram of the oil ageing test arrangement is given inFig 19.10 For applications with long oil-drain intervals the oil ageing test was devel-oped using C-type gears under different load, speed, and temperature conditions.Lubricants are exposed to conditions of load and speed of bearings and gearsencountered in standard transmissions, and in a spray lubrication device, to elevatedoil temperatures of 110 to 130 C for enhanced thermal degradation over the run-time The oil-ageing properties and their effect on performance under these high-temperature conditions and in other component tests after ageing are correlatedwith those of reference oils The different oil application-related ageing test methodsare described elsewhere [19.34] After the shortened duration of oil ageing in theFZG rig (Fig 19.11) the oil is tested to determine the behavior of critical compo-nents Different component test results for commercial brands are discussed else-where [19.13, 19.14, 19.35] Further correlations of automatic transmission fluidssynthetically aged with FZG test methods to evaluate wet clutch friction stabilitycompared with results from field trials are also given elsewhere [19.36] By use ofthese test results oil-specific and application-specific lifetime limits, i.e “logarithmicoil temperature/ageing time curves’’ can be derived, enabling determination of theeffect of temperature on lifetime for each of the critical component

Oil supply 2 to 3 l min -1

Oil return system

Total oil volume max 25 to 30 l

Load clutch

Oil ageing operating conditions

- Oil injection lubrication

Heating

Oil injection

Oil tank Gear pump Shaft 2 ( torsion rod )

Fig 19.10 FZG back-to-back gear-test rig with modified oil ageing set-up.

758 19 Mechanical–Dynamic Test Methods for Lubricants

ATF synthetically aged in the FZG rig [ h ]

Roadway of transmissions in the field trial

Curve of synthetically aged ATF in the FZG rig at higher oil sump temperatures with DKA rig friction characteristics identical with those of the ATF used for field trials with lower average oil sump temperatures

Fig 19.11 Shortened duration of oil ageing in the modified FZG rig.

When using the FZG oil-ageing procedure the analytical figures must be taken as

an indication of oil modifications that can result in different possible effects onlubricant performance and the capacity in the different components These effectsare strongly dependent on the oil type and the additives For a specific investigation

of the effects of extended oil drain intervals the oil-specific and application-specificlifetime-limiting criterion must be known, e.g from damage or from long terminvestigation of the application Aged samples from the application run underknown temperature and duration conditions are also necessary for calibrating theageing conditions in the test rig described elsewhere [19.36]

19.4

Performance Tests for Roller Bearing Applications

19.4.1

FAG Roller Bearing Test Apparatus FE8

The FAG Roller Bearing Test Apparatus FE8 is one of the most versatile test rigs forlubricants The machine itself is specified in DIN 51819 part 1 [19.37, 19.38] Themethod specified serves to test lubricants such as lubricating oils part 3 and greases

of NLGI classes 1 to 4 (in accordance with DIN 51818 part 2 [19.39]) to assess theeffect which these lubricants have under service conditions on the frictional behav-ior and wear of angular contact groove ball bearings, tapered roller bearings andcylindrical thrust roller bearings (cylindrical axial roller bearings) A schematic dia-gram of the test head and drive unit of the FE8 is shown in Fig 19.12 Two testbearings are mounted in the FE8 test head, subjected to a given axial bearing load

759 19.4 Performance Tests for Roller Bearing Applications(thrust load equivalent to 10, 20, 50, 80, or 100 kN), operated at a given speed (vari-able from 7.5 to 3000 rpm), and kept, by means of a heating and/or cooling system,

at any required operating temperature between ambient temperature and 200 C.The operating temperature must be a multiple of 10 C Newer FE8 machines areequipped with an additional cooling device that enables use of test bearing tempera-tures of –20 C If testing oils or greases with external heating, the heating system isswitched on after a short running-in time when the test is started Grease testing iscontinued until a loading time of 500 h has elapsed or until lubrication of the bear-ings becomes inadequate and the test bearing friction torque assumes the switch-offtorque for at least 10 s, when the apparatus will switch off automatically For opera-tions beyond a loading time of 500 h, the loss in mass of the rolling elements and ofthe bearing cages (wear) is used to assess the anti-wear characteristics of the grease

If testing lubricating oils, an external oil circulation system is added A defined oilflow rate (150 to 250 mL min-1, total oil volume 5 L) is specified for a bearing oilinlet temperature of 80 to 120 C The duration of the oil-test procedure is 80 husing the thrust cylindrical roller bearings (FE8 wear test)

Test head shaft

Disc spring assembly ( thrust load )

Oil supply ( lubricating and cooling )

Spacer for thrust load adjustment

Bearing retainer

at loading end

Cooling device

Fig 19.12 Schematic diagram of the FE8 test head (oil test).

Bearing geometries of 60 mm (inner race diameter) have sufficient bearing sizeand mass to determine lubricant-dependent mass losses of roller elements, bearingraces, and the cage with sufficiently precise values for repeatability and reproducibil-ity Variation of cage material (e.g polyamide, brass, or steel) even enables determi-nation of the lubricant-dependent wear protection of different materials on steelcontacts for greases and lubricating oils

The current FE8 roller bearing test apparatus is also suitable for testing bearingfatigue life (pitting load capacity) in mixed-lubrication regimes Investigations havebeen reported elsewhere [19.40] FVA project no 504 [19.41] evaluates new test pro-cedures reported elsewhere [19.42] with modified test heads The most important

760 19 Mechanical–Dynamic Test Methods for Lubricants

common test standards and test machines for performance tests of lubricated ings are summarized in Table 19.9

bear-Tab 19.9 Test standards for roller bearing applications.

FAG roller bearing

test apparatus FE8

Test using the FAG roller bearing testing apparatus FE8

General working principles Testing of lubricating greases Testing of lubricating fluids

DIN 51819 DIN 51819, Part 1 DIN 51819, Part 2 DIN 51819, Part 3

ZF bearing pitting test Determination of oil influence on pitting load capacity of cylinder roller thrust bearings on mixed-lubrication

ZF 702 232/2003

VW TL52512/2005

VW TL52182/2005

FAG roller bearing

test apparatus FE9

Test using the FAG roller bearing testing apparatus FE9

General working principles Test method A/1500/6000

DIN 51821 DIN 51821, Part 1 DIN 51821, Part 2 FAG spindle bearing

protection by lubricating greases

apparatus

Noise inspection of lubricating greases (computer-aided)

SKF specification MVH 90 B

19.4.2

FAG Roller Bearing Test Apparatus FE9

The FAG roller bearing test apparatus FE9 has been developed for testing greasesunder application-relevant operating conditions The service life of the grease isdetermined from the operating temperature, the load, and the rotational speed ofthe test bearing A schematic diagram of the FE9 test machine and cap assembly areshown in Fig 19.13

761 19.4 Performance Tests for Roller Bearing Applications

Fig 19.13 Schematic diagram of the FE9 test head (grease

test) and cap assembly A Open cap assembly, B Covered cap

without grease reservoir assembly, C Covered cap with grease

reservoir assembly.

The machine is specified in DIN 51821 part 1 [19.37, 19.38] The test method A/1500/6000 has been standardized in DIN 51821 part 2 (Table 19.9) The angular con-tact ball-bearing in the test head is filled with approximately 2 mL grease The testbearing is loaded with a thrust load (axial test force) of 1500 N at a speed of

6000 rpm The test temperature can be selected within the range 120 to 200 C(maximum) and is applied to the test bearings by means of heating elements Thesehigh temperatures of the tested greased bearing facilitate oxidation of the lubricant.Failure of a lubricant in the test bearing results in an increase in the required powerinput of the drive motor Exceeding a given limit results in automatic shut-off of onetest head, which means the duration of one test run has been determined For oneFE9 test, statistical evaluation is performed for five test runs on five different testheads, all operated under identical conditions; five (slightly) different test results

762 19 Mechanical–Dynamic Test Methods for Lubricants

(run-times) are used for statistical determination of the 50 % probability of failure bythe method of Weibull [19.20] The average duration is regarded as the service life ofthe grease The test conditions are regarded as having been selected correctly if 50 %probability of failure occurs after 100 to 200 h After >300 h the test run usuallystops automatically

In a deviation from the standard, the speed can be reduced to 3000 rpm and thethrust load enhanced to 3000 or 4500 N to perform tests under intensified mixed-lubricated conditions In practice, under all operating conditions it is accepted that

at an operating temperature >100 C, increasing the operating temperature by 10 to

15 degrees halves the service life of the grease in roller bearings It is not useful torun wear or fatigue endurance tests using the FE9 machine, because the size of thetest bearings is too small for gravimetric determination of wear or pitting and thisleads to a relatively large spread of test results Under FE9 test conditions (applica-tion-related operating conditions), the nominal bearing life of the loaded test bear-ing (calculated and statistically validated in terms of fatigue life in catalogues ofbearing manufacturers) is, furthermore, much longer than the service life of greasesmeasured and determined in the FE9 apparatus

19.5

Performance Tests for Synchronizer Applications

19.5.1

Area of Application

Manual transmissions are a common source of complaint from car drivers because

of poor or hard shifting For that reason, OEM pays increasing attention to the tion properties of the synchronizing elements Component harmonization andmass production imply that the same gearbox model must accommodate a widerange of different driving patterns In the field there are large variations betweenminimum and maximum operating conditions and, therefore, different expecta-tions of shifting characteristics More compact vehicles with smaller engines andbetter fuel economy require a wider range of gear ratios Larger gears are used forthe lower ratios, increasing the demand for synchronizers operating between shifts.There is more inertia to be stopped but not much more space to accommodate thesynchronizer Hence the development of double and triple cone synchronizers, mul-tiplying the number of friction surfaces, enabling design to be kept compact Thedemand on friction is, however, increased, because there is more energy to dissipate

fric-in a tighter volume [19.43–19.45]

19.5.2

Function of the Synchronizer

Synchronizer components are housed in the gearbox and its role is vital in the ing process in a synchronized gearbox It is used to accelerate the gear to be engaged

shift-763 19.5 Performance Tests for Synchronizer Applications

so that it can quietly mesh with the driving gear when rotating speeds are nized Synchronizers can be described as mechanical brakes They are commonlyconical in shape and have grooves to break the oil film, to provide some cooling, and

synchro-to furnish a complicated surface pattern for best braking grip Many differentdesigns have been developed over the years to enable smooth and rapid gear engage-ment Several factors potentially play a role in their performance, including machin-ing and manufacturing processes Synchronizer material is certainly an importantfactor in providing the correct friction properties in constant evolution Its composi-tion, component geometry and manufacturing conditions are jealously guardedsecrets from all the different suppliers on the market Typical shifting time rangesfrom a few tenths of a second in a passenger car to less than 50 ms in racing vehi-cles Comfort is less of a priority in the latter application, which enables use of moredirect systems that would otherwise be rejected as too harsh by the average driver.Although the details of the operation are complex, they are totally transparent to thedriver, except when the synchronizer does not perform its duty properly, causinggear clashing [19.46] The customer’s expectations increase as rapidly as the technol-ogy improves New solutions must constantly be developed or further enhanced toprovide faster and smoother shifting There is therefore a need for standardized testrigs Figure 19.14 gives examples of synchronizer systems in current use

Single and double cone synchronizers Triple cone synchronizers

Fig 19.14 Synchronizer systems currently in use.

19.5.3

Standardized Test Rigs and Test Methods

A very limited range of three standardized rigs, so-called “Synchromesh’’, for mance evaluation are currently available commercially These are the l-comb rigsand the FZG SSP180 rig Testing conditions with this equipment always try to

perfor-764 19 Mechanical–Dynamic Test Methods for Lubricants

match today’s gearbox operating environment, particularly in terms of dynamic formance and performance optimization For both types of rig the test componentscan either be taken out of regular production or can be accurate pre-measured andselected parts Use of a hardware set of known performance (for example the Audi,New Venture Gear, ZF or DaimlerChrysler synchronizers) enables determination ofthe effects of different lubricants on synchronizer endurance for manual and dual-clutch gearboxes in automotive applications defined by wear and change in the coef-ficient of friction As fluid formulations change to address new or greater perfor-mance requirements in other areas of the transmission, information provided bythese test procedures will enable lubricant formulators to determine whether syn-chronizer performance will remain acceptable

per-Subjecting these units to thousands of engagements serves to test synchronizerdurability Different types of synchronizer and friction material are used by theOEMs; area of application currently affect service life It is not possible to create onegeneral standard test procedure for approval purposes OEMs require a commontest procedure which enables understanding of oil manufacturers’ test results Thetest procedures given by CEC L-66-T-99 for the SSP180 are suitable for use as

“screening tests’’ for this purpose [19.47] Different types of synchronizer can beused and a variety of procedures are available depending on the application (passen-ger car or heavy duty vehicles, and/or materials, summarized in Table 19.10) Gearclashing, synchronizer wear, or synchronizer seizure are the main types of failureobserved for this equipment, in agreement with most field experience [19.48].Tab 19.10 Test standards and synchronizer materials for oil tests.

Audi ML 310 Carbon 5010, double cone, passenger car

VW DK 67, HS45, double cone, passenger car

ZF TK 89, triple cone, HS45

ZF, Audi, VW, New Venture Gear, Getrag, BMW, Ford, GM, Fiat OEM Specifications

FZG SSP180

synchronizer

testing machine

AUDI B 80 brass, single cone, passenger car

ZF BK 117 HS45, single cone, light truck

ZF BK 119 molybdenum, single cone, light truck

DC AK 177 molybdenum, single cone, HD Appl.

CEC L-66-T-99

19.5.3.1 l-Comb Synchronizer Testing Machine

The l-comb synchronizer testing machine was developed by the Hrbiger Company

in Schongau (Germany) [19.49] This machine uses a single synchronizer set andoperates up-shift during testing To keep operating conditions as close as possible tothe real gearboxes, the rotation speed changes direction every 200 revolutions Dif-ferent types of synchronizer can be used and different procedures are availabledepending on the application (passenger car or heavy-duty vehicles, and/or materi-

765 19.5 Performance Tests for Synchronizer Applications

for force and torque

Solid base plate

Synchronizer assembly

Shaft with spline

Shift fork

Oil supply Hydraulic

cylinder Linear potentiometer

Speed sensor

Fig 19.15 Schematic diagram of the l-comb synchronizer testing machine.

als) The rig characteristics are well suited for measurement and development ofdouble and triple cone synchronizers The most widely recognized version is thesmall l-comb option A bigger version of this testing machine, the l-comb truck, isused for testing synchronizers of commercial vehicles A schematic diagram of theoperating principle is shown in Fig 19.15 The main technical data are given inTable 19.11

Tab 19.11 l-Comb synchronizer testing machines.

This machine uses a single synchronizer set and operates up-shift during testing.The test machine consists of an electric motor, flywheels, actuating hydraulics, anoil heating and circulation system, and a test box The flywheels are connected tothe electric motor via a clutch to ensure a constant and stable source of speed Theflywheels are the load the synchronizers bring to a shift to “speed zero’’ position to

be accelerated after this shifting back to a constant speed by the motor again This isaccomplished by the ring-and-cone synchronizers mounted in the test box Theactuating hydraulics move a shift fork that engages and disengages the unit During

766 19 Mechanical–Dynamic Test Methods for Lubricants

shifting, heated lubricant is sprayed on to the synchronizer unit Subjecting theseunits to thousands of engagements serves to test synchronizer durability and fric-tion

19.5.3.2 FZG SSP180 Synchronizer Testing Machine

The most widely recognized tool is the FZG SSP180 synchronizer testing machine,developed by the Hurth Company and now built, distributed, and supported by the

ZF in Passau (Germany) [19.50] This machine uses a complete synchronizer setand operates full up and down-shift during testing The test machine consists of anelectric motor, two flywheels, actuating hydraulics, an oil heating and circulationsystem, and a test box The large main flywheel is connected to the electric motorvia a belt-and-pulley combination to ensure a constant and stable source of speed.The small flywheel is the load that the synchronizers either bring to zero speed(shift to “A’’ position) or accelerate to a constant speed (shift to “B’’ position) This isaccomplished by the two ring-and-cone synchronizers mounted in the test box Therear unit accelerates the load flywheel to synchronous speed while the forward unitdecelerates the flywheel to zero speed The actuating hydraulic moves a shift forkthat engages one unit and disengages the other During shifting, heated lubricant issprayed on to both synchronizer units

A schematic diagram of the FZG SSP180 machine is shown in Fig 19.16 Typicalsynchronizer engagement traces showing individual shift performance data are il-lustrated in Fig 19.17 Data from the engagements are plotted during the course ofthe test and the trends observed show whether or not performance is degrading.Technical data for the machine are listed in Table 19.12

Electric motor

wheel

Fly-Hydraulic cylinder

Flywheel for acceleration and deceleration

Speedo-Sliding collar