Tribology Handbook 2 2010 Part 9 pot

Plain bearing lubrication e7 Mineral oils a n d greases are the most suitable lubricants for plain bearings in most applications.. Rolling bearing lubrication C8 Table 8.7 General guide

C6.6

Plain bearing lubrication e7

Mineral oils a n d greases are the most suitable lubricants for plain bearings in most applications Synthetic oils may be required ifsystem temperatures are very high W a t e r a n d process fluids c a n also be used as lubricants in certain applications

T h e general characteristics of these m a i n classes of lubricants a r e s u m m a r i s e d i n T a b l e 7.1

Table 7.7 Choice of lubricant Table 7.2 Methods of liquid lubricant supply

~~

Lubricant Operating range Remarks

Mineral All conditions of Wide range of viscosities

oils load and available Potential

speed corrosion problems

with certain additive oils (e.g extreme pressure) (see Table 7.9) Synthetic All conditions if Good high and low

oils suitable temperature properties

viscosity Costly

available

Greases Use restricted to Good where sealing

operating against dirt and

speeds below moisture necessary

1 to 2 m/s and where motion is

intermittent Process Depends on May be necessary to

fluids properties of avoid contamination of

fluid food products,

chemicals, etc

Special attention to design and selection of bearing materials

T h e most important property of a lubricant for plain

bearings is its viscosity If the viscosity is too low the bearing

will h a v e inadequate load-carrying capacity, whilst if

the viscosity is too high the power loss a n d the operating

temperature will be unnecessarily high Figure 7.1 gives a

guide to t h e value of the m i n i m u m allowable viscosity for a

range of speeds a n d loads I t should b e noted that these

values a p p l y for a fluid a t t h e m e a n bearing temperature

T h e viscosity alf mineral oils falls with increasing tempera-

ture The viscosity/temperature characteristics of typical

mineral oils a r e shown i n Figure 7.2 The most widely used

methods of supplying lubricating oils to plain bearings a r e

listed in T a b l e 7.2

The tubricatinq properties of greases are determined to

a large extent by the viscosity of the base oil a n d the type of

thickener used in their manufacture T h e section of this

handbook on greases summarises t h e properties of the

various types

Additive oils a r e not required for plain bearing lubrica-

tion b u t o t h e r requirements of the system may d e m a n d

their use Additives a n d certain contaminants may create

potential corrosion problems T a b l e s 7.3 a n d 7.4 give a

guide t o additive a n d bearing material requirements, with

examples of situations i n which problems can arise

Method .f M a i n characteristics

Hand Non automatic, irregular Low-speed,

High maintenance cost bearings Drip and Non automatic, Journals in oiling Low initial cost cheap journal

wick adjustable some machine feed Moderately efficient tools, axles

Cheap Ring and Automatic, reliable Journals in collar Efficient, fairly cheap pumps, feed Mainly horizontal blowers, large

motors Bath and Automatic, reliable, Thrust bearings, splash efficient bath only

lubri- Oil-tight housing Engines,

general High initial cost machinery,

Pressure Automatic High-speed and feed Positive and adjustable heavily

Reliable and efficient loaded High initial cost journal and

thrust bearings in machine tools, engines and compressors

Notes

Pressure oil feed : This is usually necessary when the heat dissipation of the bearing housing and its surroundings is not sufficient to restrict its temperature rise to 20°C or less grooves in the bearing housing Some common arrangements are shown in Figure 7.3

pressure feed from the centre of the bearing satisfactory performance and long life

Journal bearings: Oil must be introduced by means of oil

Thrust bearings: These must be lubricated by oil bath or by Cleanliness: Cleanliness of the oil supply is essential for

C7.1

c7 Plain bearing lubrication

Table 7.3 Principal additives and

contaminants

Oxidation of IC engines Antioxidant

lubricant Steam turbines additives

Compressors High-speed gearboxes Scuffiing Gearboxes Extreme-

mechanisms additive

Deposit formation IC engines Dispersant

Compressors additives Excessive wear General

of lubricated

surfaces

Antiwear additives

Water I C engines Good

contamination Steam turbines demulsification

Compressors properties

Turbine- quality oils may be required Dirt particle IC engines Dispersant

contamination Industrial plant additives

Weak organic IC engines Acid neutraliser

acid

contamination

Strong mineral Diesel engines Acid neutraliser

acid Process fluids

contamination

Rusting IC engines Rust inhibitor

Turbines Industrial plant General

Plain journal bearings

Surface speed,

M e a n pressure, where

Plain thrust bearings

Surface speed, u = nDn, ms-'

M e a n pressure 7 = KW, kNrn-'

ID

where n = shaft speed, s-'

I = width of bearing ring, m

D = mean pad diameter, m

W = thrust load, kN

(3

Minimum allowable viscosity qrhrust = qmin,

Surface speed, ft/min

Plain bearing lubrication e7

Table 7.4 Resistance to corrosion of bearing metals

Strong mineral Synthetic

Lrnperature, “C additive Extreme-pressure Antioxidant acidc Weak organic

Lead-bronze (without overlay) 180 Good with good Good Poor Moderate Good

quality bronze

ing additives tor sulphur must not be

with suitable overlay

Note: corrosion of bearing metals is a complex subject The above offers a general guide Special care is required with extreme-pressure

lubricants; if in doubt refer to bearing or lubricants supplier

Figure 7.2 Typical viscosity,’temperature

characteristics of mineral oik

Bearing temp era ture

L u b r i c a n t supply rate should be sufficient t o restrict t h e temperature rise t h r o u g h the b e a r i n g to less than 20°C

A working estimate of t h e mean bearing temperature,

t e r m s of Kinematic Viscosities

c7.3

* At moderate speeds oil holes may be substituted if l / d does not exceed 1

Note: the load-carrying capacity of bearings with circumferential grooves is somewhat lower than with axial grooves owing to the effect

of the groove on pressure generation

Figure 7.3 Oil grooves in journal bearings

c7.4

Rolling bearing lubrication C8

Table 8.7 General guide for choosing between grease and oil lubrication

Temperature U p to 120°C-with special greases or short U p to bulk oil temperature of 90°C OF bearing

temperature of 200°C-these temperatures may

be exceeded with special oils relubrication intervals up to 20O/22O0C

Speed factor IJp to dn factors of 300 000/350 000 (depending U p to dn factors of 450 000/500 000

(drpending on type of bearing)

on design)

Bearing design Not for asymmetrical spherical roller thrust All types

bearings Housing design Relatively simple

Long periods without Yes, depends on operating conditions, especially No

More complex seals and feeding devices necessary attention temperature

Central oil supply for No-cannot transfer heat efficiently or operate Yes

other machine elements hydraulic systems

Lowest torque When properly packed can be lower than oil on For lowest torques use a circulating system with

which the grease is based scavenge pumps or oil mist Dirty conditiom

~

Yes-proper design prevents entry of con- Yes, if circulating system with filtration taminants

* dn factor (bearing bore (mni) x speed (revimin))

Note: for large bearings ( > 65 mm bore) use nd, ( d , is the arithmetic mean of outer diameter and bore (mm) )

Grease sellection

The principle factors governing the selection of greases

for rolling bearings a r e speed, temperature, load, environ-

ment and method of application Guides to the selection

of a suitable grease taking account of the above factors are

given in Tables 8.2 a n d 8.3

The appropriate maximum speeds for grease lubrication

of a given bearing type a r e given in Figure 8.1 T h e life

required from the grease is also obviously important and

Figure 8.2 gives a guide to the variation of grease

operating life with percentage speed rating and tempera-

ture for a high-quality lithium hydroxystearate grease as

derived from ]Figure 8.1 (These greases give the highest

speed ratings.)

When shock loading and/or high operating temperatures

tend to shake the grease out of the covers into the bearing,

a grease of a harder consistency should be chosen, e.g a

no 3 grease instead of a no 2 grease

Note: it should be recognised that the curves in Figures 8.1 and 8.2

can only be a guide Considerable variations in life are possible

depending on precise details of the application, e.g vibration, air

flow across the bcearing, clearances, etc

Table 8.2 The effect of the method of appli- cation on the choice of a suitable grade

Compression cups u p to 5 Centralised lubrication 2 or below

( a ) Systems with separate metering Normally 1 or 2 valves

(b) Spring return systems I

(c) Systems with multi-delivery 3 pumps

C8.1

C8 Rolling bearing lubrication

Table 8.3 The effect of environmental conditions on the choice of a suitable type of grease

Sbeed maximum Tvbical service temberatur~ / A

NLGI hercentage

l j p e of grease grade recommended Environment Maximum Minimum Base Oil u i s c o s i ~ Comments

Multi-purpose, not advised

a t max speeds or max temperatures for bearings above 65 mm bore or on

up to 140 cSt at 100°F vertical shafts

For max speeds recom- mended where vibration loads occur at high speeds Lithium E P 1 75 Wetordry 90 195 -15 5 Recommended for roll-neck

70 160) - 15 } 14.5 cSt at 210°F bearingsand heavily-load- Wetordry 9o

Calcium EP 1 and 2 50 Wetordry 60 140 -5 25 14.5 cSt at 210°F

Sodium 3 75/100 Dry 80 175 -30 -22 30cSt at 100°F Sometimes contains 20%

Clay 50 Wetordry 200 390 10 50 550 cSt at 100°F

Clay 100 Wetordry 135 275 -30 -22 Up to 140 cSt a t

100°F Clay 100 Wet or dry 120 248 -55 -67 12 cSt at 100°F Based on synthetic esters Silicone/lithiurn 75 Wet or dry 200 390 -40 -40 150 cSt at 25°C Not advised for conditions

where sliding occurs at high speed and load

Figure 8.1 Approximate maximum speeds for

grease lubrication (Basic diagram for calculating

bearing speed ratings)

.Vultipl_v bearing speed from Figure 8.1 bv t h i s , factor to get / h e maximum speed f o r each Qpe

rolling elements

Taper- and spherical- roller 0.5 bearings

Bearings mounted in 0.75 adjacent pairs

Bearings on vertical shafts 0.75 Bearings with rotating outer 0.5 races and fixed inner

races

C8.2

Rolling bearing lubrication roo 000

Packing ball and roller bearings with grease

( a ) The grease should not occupy more than one-half

to three-quarters of the total available free space in the covers with the bearing packed full

(b) One or more bearings mounted horizontally-com- pletely fill bearings and space between, if more than one, but fill only two-thirds to three-quarters of space in covers

( c ) Vertically-mounted bearings-completely fill bear- ing but fill only half of top cover and three-quarters of

Figure 8.2 \/ariation of operating life of a high-

quality grade 3 /ithiurn hydroxystearate grease with

speed and temperature

(d) Low/medium speed bearings in dirty environments -comP1etely bearing and covers

The relubrication period for ball and roller bearings may

be estimated using Figures 8.1 and 8.2 The following is an

example in terms of a typical application:

Required to know : Approximate relubrication period

for the following:

Bearing type : Medium series bearing 60 mm bore

Cage : Pressed cage centred on balls

Speed : 950 rev/nnin

Temperature : 120°C [The bearing temperature

(not merely the local ambient tem- perature) i.e either measured or

estimated as closely as possible.]

Position : Vertical shaft

Grease : Lithium grade 3,

Duty : Continuous

From Figure 8.1 : 60 mm bore position on the lower

edge of the graph intersects the medium series curve at approxi- mately 3100 revlmin

Factor for pressed cages on balls is about 1.5; thus

3100 x 1.5 = 4650 revlmin

Factor for vertical mounting is 0.75 Thus 4 6 5 0 ~ 0 7 5

= 3488 sev/min

This is the rnaximum speed rating ( 100%)

Now actual speed = 950 rev/min; therefore percentage -

9 50

348%

of maximum = -x 100 = 27% (say 25% approxi-

mately)

In Figure 8.2 the 12D"C vertical line intersects the 25%

speed rating curve for the grade 3 lithium grease at

approximately 1300 hours, which is the required answer

Relubrication of ball and roller bearings

Relubrication may be carried out in two ways, depending

on the circumstances :

( a ) Replenishment, by which is meant the addition of fresh grease to the original charge

(b) Repacking, which normally signifies that the bearing

is dismounted and all grease removed and discarded, the bearing then being cleaned and refilled with fresh grease

An alternative, if design permits, is to flush the bearing with fresh grease in situ (Grease relief valves have been developed for this purpose.)

The quantity required per shot is an arbitrary amount Requirement is only that sufficient grease is injected to disturb the charge in the bearing and to displace same through the seals, or grease relief valves

A guide can be obtained from

D x w

W = -

200 where W is quantity (g)

and w is width (mm)

D is outside diameter (rnm)

If grease relief valves are not fitted, the replenishment charge should not exceed 5% of the original charge After grease has been added to a bearing, the housing vent plug (if fitted) should be left out for a few minutes after start-up

in order to allow excess grease to escape A better method,

if conditions allow, is to push some of the static grease in the cover back into the bearing to redistribute the grease throughout the assembly This method is likely to be unsatisfactory when operating temperatures exceed about

100°C

C8.3

10.0

9.0 8.0

7.0

Generally, when speeds are moderate, the following

minimum viscosities at the operating temperatures are

recommended :

cSt

Ball and cylindrical-roller bearings 12

Spherical-roller thrust bearings 32

The oils will generally be HVI or MVI types containing

rust and oxidation inhibitors Oils containing extreme

pressure (EP) additives are normally only necessary for

bearings where there is appreciable sliding, e.g taper-

roller or spherical-roller bearings, operating under heavy

or shock loads, or if required for associated components,

e.g gears T h e nomogram, Figure 8.3, shows how to select

more precisely the viscosity needed for known bore and

speed when the operating temperatures can be estimated

If the operating temperature is not known or cannot be

estimated then the manufacturer's advice should be sought

To use Figure 8.3, starting with the right-hand portion

of the graph for the appropriate bearing bore and speed, determine the viscosity required for the oil at the working temperature The point of intersection of the horizontal line, which represents this oil viscosity, and the vertical line from the working temperature shows the grade of oil to be selected If the point of intersection lies between two oils, the thicker oil should be chosen

Examples: Bearing bore d = 60 mm, speed n = 5000 rev/

min (viscosity at working temperature = 6.8

cSt), with working temperature = 65°C Select

oil S 14 ( 1 4 cSt at 50°C approx.)

Bearing bore d = 340 mm, speed n = 500 rev/ min (viscosity at working temperature = 13.2 cSt), with working temperature = 80°C Select oil S 38 (38 cSt at 50°C approx.)

20 30 40 50 60 70 BO 90 100 110 12OoC 50 75100 200300 500 d.mm R"= Redwood No 1 seconds;

S" = Saybolt Universal seconds, SSU

E" = degrees Engler

C S t = centistokes

Figure 8.3 Graph for the selection of oil for roller bearings (permission of the Skefko Ball Bearing Co Ltd) The graph has been compiled for a viscosity index of 85, which represents a mean value of the variation of the viscosity of the lubricating oil with temperature Differences for 95 VI oils are negligible

C8.4

Rolling bearing lubrication

Application of oil t o rolling bearings

C8

Bath/splash Generally used where speeds are low Bearings on horizontal and vertical

A limit in dn value of ooo is some- element shafts, immerse half lowest rolling times quoted, but higher values can

be accommodated if churning is not Multi-row bearings on vertical shafts,

a problem fully immerse bottom row of

elements Oil flingers, d r i p feed Normally as for bath/splash Flow rate dictated by particular Allows use of lower oil lubricators, etc application; ensure flow is sufficient level if temperature-

rise is too high with

to allow operation of bearing below desired or recommended maximum bath/splash temperature - generally between

70°C and 90°C

Pressure circulating No real limit to dn value

Use oil mist where speeds are very high

As a guide, use:* 0.6 cm3/min cmz of T h e oil flow rate has projected a r e a of b e a r i n g generally to be de- (0.d x width) cided by considera-

tion of the operating temperature Oil mist No real limit to dn value

Almost invariably used for small bore bearings above 50 000 revlmin, but also used at lower speeds

As a guide, use:* 0.1 to 0.3 x bearing bore (cm/2.54) x no of rows-cm3/

hour Larger amounts are required for pre- loaded units, up to 0.6 x bearing bore (cm/2.54) x no of rows-cm3/

hour

In some cases oil-mist lubrication may be combined with a n oil bath, the latter acting as a reserve supply which is par-

t i c u l a r l y valuable

w h e n high-speed bearings start to run

* It must be emphasised that values obtained will be very approximate and that the manufacturer's advice should be sought on the performancc of equipment of a particular type

C8.5

Gear and roller chain lubrication

Pitch line speed, ft/min

Pitch line speed, m/s

Figure 9 I Selection of oil for industrial enclosed

gear units

Figure 9.1 is a general guide only It is based on the

criterion: Sc HV/(Vp + 100)

where Sc = Surface stress factor

Load/inch line of contact Relative radius of curvature

HV = Vickers hardness for the softer member of the

-

and

gear pair

Vp = Pitch line velocity, ft/min

The chart applies to gears operating in an ambient tem-

perature between 10°C and 25°C Below 10°C use one grade

lower Above 25°C use one grade higher Special oils are

required for very low and very high temperatures and the

manufacturer should be consulted

With shock loads, or highly-loaded low-speed gears, or

gears with a variable speed/load duty cycle, EP oils may

be used Mild EPs such as lead naphthanate should not be

used above 80"C( 170°F) running temperature Full hypoid

EP oils may attack non ferrous metals Best EP for normal

industrial purposes is low percentage of good quality

sulphur/phosphorus or other carefully inhibited additive

Pitch line speed, m/s

Figure 9.2 Selection of oil for industrial enclosed worm gears

Suitable lubricants for worm gears are plain mineral oils

of a viscosity indicated in Figure 9.2 It is also common practice, but usually unnecessary, to use fatty additive or leaded oils Such oils may be useful for heavily-loaded, slow-running gears but must not be used above

80°C( 170°F) running temperature as rapid oxidation may

occur, resulting in acidic products which will attack the bronze wheel and copper or brass bearing-cages

Worm gears do not usually exceed a pitch line velocity

of 2000 ft/min, but if they do, spray lubrication is essential The sprayed oil must span the face width of the worm

7 5 x 1 0 d x C * Pressure kN/m2 100 170 270 340 m3/sec

C* = centre distance in metres

Q = C/4 gpm Pressure lbf/in2 15 25 40 50

Where C = centre distance, inches

Recent developments in heavily loaded worm gear lubrica- tion include synthetic fluids which:

( a ) have a wider operating temperature range (b) reduce tooth friction losses

( 6 ) have a higher viscosity index and thus maintain an oil film at higher temperatures than mineral oils

(d) have a greatly enhanced thermal and oxidation stability, hence the life is longer

Even mcire recent developments include the formulation

of certain soft synthetic greases which are used in 'lubri- cated-for-life' worm units Synthetic lubricants must not

be mixed with other lubricants

c9.1

Gear and roller chain lubrication C9

N O ~ : * T h e min viscosity at 0°F may be waived if the viscosity is

not less than 7 cSt at 210°F

These values are approximate and are given for information only

Selection of lubricants for

transmissions and axles

Almost invariably dip-splash

T h e modern tendency is towards universal multipurpose

oil

Rear axles Manual Automatic Rear axles (spiral

gear boxes gear boxes (hypoidr) bevel and

EP or multi- purpose (ATF)

S A E 8 0 E P -

for semi- auto- matics ATF fluid for autos

SAE 140

or multi- pur- pose

Above only to be used where supplier's recommenda-

tions are not available

Above are suitable for normal conditions In cold

conditions ( < 0°C) use one SAE grade less In hot

conditions ( > 40°C) use one SAE grade higher

In most cases (except hypoids), straight oils are accept-

able The above EPs are given for safety if supplier's

recommendations are not known

Some synthetic (polyglycol) oils are very successful with

worm gears They must not be mixed with any other

oils ATF fluids must not be mixed with others

Change periods: (only if manufacturer's recommenda-

tions not lmown) Rear axles-do not change Top up

as required All manual and automatic gearboxes-

change after 20000 miles Before that top up as required

ROLLER CHAINS

Type of lubricant: Viscosity grade no 150 ( I S 0 3448)

For slow-moving chains on heavy equipment, bituminous viscous lubricant or grease can be used Conditions of operation determine method of application and topping-

u p or change periods Refer to manufacturer for guidance under unusual conditions

OPEN GEARS

Applies to large, slow-running gears without oil-tight housings

Methods of Requirements of Type.r of lubricant application

lubricant

Must form protective Generally bituminous

Sometimes cut back

by volatile diluent heavy EP oils

Must not be squeezed out Can use grease or Must not be thrown

O f f

Hand, brush, paddle Dip-shallow Drip-automatic Spray- continuous or intermittent P"'

~

Must be suitable for prevailing ambient conditions

Viscosity ofopen gear lubricant CS at 38"C( 1OO"fl

"C

Residual Mild EP oil comPOund Mild EP oil

5 to 35 100-120

25 to 50 18CL2QQ

C9.2

CIO Slide lubrication

Slides are used w h e r e a linear motion is required between

two components An i n h e r e n t feature of this linear motion is

t h a t parts of the w o r k i n g surfaces must be exposed d u r i n g

operation T h e selection of methods of slide lubrication

must therefore consider not only the supply and retention of

lubricant, b u t also the protection of the working surfaces

from dirt contamination

Slides and linear bearings on To reduce friction and wear at the Greases and solid lubricants are The sliding contact area

should be protected from dirt by fitting scraper seals

packaging machines, textile

machines, mechanical

moving surfaces without con- taminating the material being

commonly used but air lubri- cation may also be possible

Crossheads on reciprocating T o give low friction and wear by The same oil as that used for the Oil grooves on the stationary engines and compressors maintaining an adequate film bearings surface are desirable to help

to provide a full oil film to thickness to carry the impact

Table 10.2 The lubrication of various types of linear bearings on machine tools

Type of linear bearing Suitable lubricant Method of applying the lubricant Remark5

Plain slide ways Cutting oil By splash from cutting area Only suitable in machine tool applications

using oil as a cutting fluid

Mineral oil By wick feed to grooves in the shorter Requires scraper seals at the ends of the containing polar component moving component to exclude swarf additives to reduce

boundary friction

By rollers in contact with the bottom face ofthe upper slide member, and contained in oil filled pockets in the lower member

Only suitable for horizontal slides Requires scraper seals at the ends of the moving component to exclude swarf

By oil mist Air exhaust keeps the working surfaces clear

of swarf Grease By grease gun or cup, to grooves in Particularly suitable for vertical slides, with

thesurfaceoftheshortercomponent occasional slow movement Hydro-static plain Air or any other con- Under high pressure via control Gives very low friction and no stick slip slideways veniently available valves to shallow pockets in the combined with high location stiffness

surface of the shorter member

Linear roller bearings Oil Lower race surface should be just Not possible in all configurations Must be

covered in an oil bath protected from contamination Grease Packed on assembly but with grease Must be protected from contamination

nipples for replenishment c10.1

Lubrication of flexible couplings c11

FILLED COUPLINGS (GEAR, SPRING-TYPE, CHAIN)

ble f 1 1 Recommendations for the lubrication of filled couplings

Limiting criteria Centn fuga1 Effects

acceleration practical Dissipation period

is more mechanically stable than No 1

d = pcd, m; D = pcd, ft; w = rads/sec; n = revisec; P = h p transmitted

Limits

Grease lubrication, set by soap separation under centrifug-

ing action Semi-fluid grease lubrication, set by heat

c11 Lubrication of flexible coudinrrs

CONTINUOUSLY-LUBRICATED GEAR

COUPLINGS

Lubrication depends on coupling type

Figure 11.3 Dam-type coupling with anti-sludge

Wire rope lubrication c12

THE ADVANTAGES OF

LUBRICATION

Increased fatigue life

Correct lubricants will facilitate individual wire adjust-

ment to equalise stress distribution under bending con-

ditions An improvement of up to 300% can be expected

from a correctly lubricated rope compared with a similar

unlubricated rope

RANGE OF EXPECTED IMPROVEMENT

P

c

"

PETROLATUM SOFT SEMI- HARD

TYPES BITUMINOUS BITUMINOUS

TYPES TYPES TYPE OF LUBRICANT

Figure 12.1 Percentage increases in fatigue life of

lubricated rope over unlubricated rope

Increased corrosion resistance

Figure 12.2 Typical effect of severe internal corro-

sion Moisture has caused the breakdown of the fibre

core and then attacked the wires at the atrandcore

interface

Figure 12.3 Typical severe corrosion pitting as- sociated with 'wash off' of lubricant by mine water

Increased abrasion resistance

Figure 12.4 Typical abrasion condition which can be limited by the correct service dressing

LU B R lCATl0 N D U RING MANUFACTURE

The Main Core Fibre cores should be given a suitable dressing during their manufacture This is more effective than subsequent immersion of the completed core in heated grease

Independent wire rope cores are lubricated in a similar way to the strands

The Strands The helical form taken by the individual wires results in a series of spiral tubes in the finished strand These tubes must be filled with lubricant if the product is

to resist corrosive attack The lubricant is always applied

a t the spinning point during the stranding operation

The Rope A number of strands, from three to fifty, will form the final rope construction, again resulting in voids which must be filled with lubricant The lubricant may be applied during manufacture at the point where the strands are closed to form the rope, or subsequently by immersion through a bath if a heavy surface thickness is required Dependent on the application the rope will perform, the lubricant chosen for the stranding and closing process will be either a petrolatum or bituminous based compound

For certain applications the manufacturer may use special techniques for applying the lubricant

Irrespective of the lubrication camed out during rope manufacture, increased rope performance is closely asso-

ciated with adequate and correct lubrication of the ropr

in service

(32.1

c12 Wire rope lubrication

LUBRICATION OF WIRE ROPES I N SERVICE

Typical Cranes and derricks Mine haulage, Cranes and grabs, Lift suspension, Pendant ropes for

ships, on draglines, ropes, piling, and governor excavators Guys docksides, or in scrapers and percussion and ropes, mine for masts and

requirements to rope interior properties Good to rope interior Good penetration protection

Ability to displace adhesion to rope Good lubrication to rope interior Resistance to moisture Resistance to properties Ability to ‘wash off ’

Internal and removal by Resistance to displace Resistance to external mechanical ‘fling off’ moisture surface cracking

Resistance to

Resistance eo emulsification

corrosion

containing soft grease lubricating oil temporary bituminous solvent leaving containing of about SAE corrosion compound with

a thick MoS, or 30 viscosity preventative solvent added

additives can

be of advantage

* The periods indicated are for the general case The frequency of operation, the environmental conditions and the economics of service dressing will more correctly dictate the period required

APPLICATION TECHNIQUES

Ideally the l u b r i c a n t should be applied close to the point

where the s t r a n d s of the rope tend to open w h e n passing

/

/’

// ,/

/ over a sheave or drum

The l u b r i c a n t m a y b e applied manually or mechanically

c12.2

Wire rope lubrication

Manual - By can or by aerosol

Figure 1.26 Manual application by can

Mechanical-By bath or trough

By drip feed By mechanical spray

Figure 12.7 Mechanical application by trough

Figure 12.8 Drip lubrication

CHECK VALVE OPTIONAL PREVENTS DRIPPING FOR VERTICAL FEED

C13 Selection of lubrication svstems

For brevity and convenience the vast array of lubrication systems have been grouped under nine headings These are each

more fully discussed in other Sections of the Handbook

I

Centralised

I

1 automatic

Wick Type E

Selection of lubrication systems c13

Table 13.1 Oil systems Table 13.3 Relative merits of grease and oil systems

=YP Characterzstics Application

H a n d Oil can Simple bearings,

Dip Ring or disc Plain bearings-

C T y p e F systems Oil slow or

N

T Wick Pad or wick feed Plain bearings,

A T y p e E from low duty

Circulating Oil from tank or Almost all

T y p e J sump fed by applications

pressure p u m p where cost is

Rolling bearings, some plastic bushings

Local - hand Grease nipple to

T y p e B, each beariilg

Small numbers, easy, access, cheap Centralised - Feed pipes

h a n d brought to

T y p e B, manifold or

Pump Centralised - Grease pump

automatic feed to bearing

Type c and sets of

bearings from automatic Pump

Reasonable

nu rn bers

l n a ( ( w i h I c

bearings Large numbers, important bearings, great distances

Where frequent relubrication

systems can flush seal

greases

- Very high speeds No Except small Yes

rolling bearings

Hydrostatic bearings- yes Rubbing plain Yes Yes With limited

_ _ _ _ ~ ~ _ _ _ _ _

May be designed to remove almost any amount of heat

C13.2