Illustrated Sourcebook of Mechanical Components Part 14 docx

27- 14 Means o f determining liquid level, detection of changes in liquid level, transmission of indicated levels.. o r warnings of changes heyond set limits; and means of using leve

Creative Assemblies 27- 11

, Diuphragms

Piston

Double-acting actuator provides for

thrust in either direction by placing

two diaphragm assemblies back to back

Diap n raynm

Regulating valve controls the value ot air

pressure by means of a diaphragm-bal-

4 anced valve and two control diaphragms

Shaft seal uses lubricant pressure to

force the sidewall of the diaphragm to

8 roll against the shaft and housing

Double-acting pump has two diaphragms

to give smooth and continuous flow of fluid

5 to equipment at a safe working pressure

Damping mechanism prevents abrupt or

sudden motion in a machine Damping

9 amount is controlled by orifice size

27- 12

Vibration and Shock

Critical adjustments stay put-safe against accidental turning

or deliberate fiddling with them

Frank William Wood JR

a S P L I T YOKE clamps on shaft when

eccentric squeezes ends of yoke together

Knurled knob is handy for constant use, and

eliminates need for tool Another advantage

is high torque capacity But this design needs

considerable space on panel

2 FINGER springs into place between gear

te h at turn of cam Although gear lock is

ideally suited for right-angle drives, size

of teeth limits positioning accuracy

3, SPLIT BUSHING tightens on control shaft, because knurled knob has tapered thread Bushing also mounts control to panel, so requires just one hole Lever, like knob, does away with tools, but locks tighter and faster For controls adjusted infre- quently, hex nut turns a fault into a n ad- vantage Although it takes a wrench to turn the nut, added difficulty guards against knob- twisters

' Control shaft Hex nut-'

4 CONSTANT D R A G of tapered collar on

shaft makes control stiff, so it doesn’t need

locking and unlocking Compressed lip both

seals out dust and keeps molded locking nut

from rotating

Creative Assemblies 27-13

5 T O N G U E slides in groove, clamps down

on edge of dial If clamp is not tight, it can scratch the face

6 , SPOT-BRAKE clamp

is self-locking, which means it takes two hands

to make an adjustment, one to hold the clamp open and one to turn the dial

27- 14

Means o f determining liquid level,

detection of changes in liquid level,

transmission of indicated levels o r

warnings of changes heyond set limits;

and means of using level changes for

level control, or control of other con-

ditions such a5 temperature and pres-

sure, have been accomplished by numer-

ous mechanisms The most pcpular

devices employ floats or pressure meas- urement with instruments such as the U-tube manameter, bourdon tube, and bellows

The methods shown here are largely indicating methods or simple devices for automatic control of liquid level al- though they can conceivably be applied

to control other conditions such as tem-

perature a n d pressure Methods using electric resistance of a column of liquid and measurement of pressure changes

by means of piezo-electric crystals are

not shown Patent No 2,162,180 de- scribes a method involving determina- tion of change in air pressure when a

measured volume nf air is introduced into a tank

Fig 1 -Float and Lever- Operated Pilot Valve

Sfof for f i o a t counterweigh f ann Sfop for f/oaf , 1

movemen f '

fed or dece/erated movements ofplunger

for any floaf movemen

U

Fig.2-Float and Cam-

Operated Pilot Valve

Bourdon tube sqpporfs magnefic core in re-

I/ - tube)

4 i r e connecfion

fo gafvano- meter in receiver

Fig.4-Float and Pulley Indicator Fig.5-Pressure Dome Indicator-

Creative Assemblies 27- 1 5

Sec+/ona/ view excepf for weigbfs and ffoaf

Fig 6-Float Control o f Discharge

Tape visible Vapor- figh f

covers /

through

window

Tank floor, At-Pu//ey frome supporf

Fig 8-Tank Roof Indicator

_- - -.-.-.-

-

Fig.7-U-Tube Manometer with Water Columns

Double bdancing mechanism fUfs mercury

swifcbes for u/arms when refri eranf i s

be/ow eifher operufing or idle &e/s

- -Groo ves

: -F/oafing frigerun f sdmpling reservoir

Fig.10 -Refrigerant Balance

Either method can

DXAPHRAQM ACTUATED INDICATOR Can be used with BUBBLER TYPE RECORDER measures height E can

a n y kind of liquid, whether it be flowing, turbulent, or be used with a11 kinds of liquids, including those carry-

carrying solid matter Recorder can be mounted above or ing solids Small amount of air is bled into submerged

belnw the level of the tank or reservoir pipe Gage measures pressure of air that displaces fluid

BELLOWS ACTUATED INDICATOR Two bellows and

connecting tubing are fllled with incompressible fluid Change

in liquid level 'displaces transmitting bellows and pointer

I i L/,51 Use terminol5 forpumpdown, terminal 3 for ourno-uo control

f

ELECTRICAL T Y P E LEVEL CONTROLLER Positions

of probes determine duration of pump operation When liquid touches upper probe, relay operates and puinp stops Through auxiliary contacts, lower pmbe Pro-

vides relay holding cdrrent until liquid drops below It

LEX When liquid reaches predeter-

mined level, float actuates switch

through horseshoe-shape arm Switch

c/ - - , - -

_ _ _ - -

AUTOMOTIVE TYPE LIQUID LEVEL INDICATOR Indicator and tank U n i t are

connected by a single wire As liquid level in tank increases, brush contact on tank rheostat moves to the rlght, introducing an increasing amount of resistance into circuit that grounds the "F" coil Displacement of needle from empty mark

to

FLOAT TYPE RECORDER MAGNETIC LIQUID LEVEL CONTROLLER DIFFERENTIAL P R E S S U R E SYSTEM

Pointer can be a t t w h e d to a When liquid level is normal, common-to-right Applicable to liquids under pressure

calibrated float tape to give Measuring element is mercury manometer

a n approximate hstantane- level drops to predetermined level magnetic Mechanical or electric meter body can be

ous indication of fluld level Piston is drawn below the magnetic field used Seal pots protect meter body

leg circuit of mercury switch is closed When

t of ocfuofing, Pressure gouge

DIRECT READING FLOAT TYPE GAGE Inexpensive,

direct-reading gage has dial calibruted to tank volume

Comparable type as far as simplicity Is concerned h a s

needle connected through a right-angle a r m to float As

liquid level drops, float rotates the a r m and the needle

PRESSURE UAUE INDICATOR for open vessels Pressure

of liquid head is imposed directly upon actuating element of

pressure gage Center line of the actuating element must conincide wlth the minimum level line if the gage is to read zero when t h e liquid reaches the minlhum level

Heoter wire-

Bimetal strip - -

7,

BIMETALLIC TYPE INDICATOR When tank is empty, contacts in tank unit

just touch With switch closed, heaters cause both bimetallic strips to bend This

opens contacts in tank and bimetals cool, closing circuit again Cycle repeats about

once per s e a As Hqutd level increases float forces cam to bend tank bimetal Action

is simllar to previous case, but current and needle displacement are increased

rank

-Float

SWITCH ACTUATED LEVEL CON-

TROLLER Pump is actuated by

switch Float pivots magnet 40 that upper pole attracts switch contact

Tank wall serves as other contact

27-18

No tools needed to install these hangers made of wire, rod or bar-stock

L Kasper

CLIP is most secure when tubing of right size

helps keep it spread To install, hook one side

over edge of slot and spring in other side

EDGE HANGER doesn’t have to be sprung, but requires enough clearance above holes so

that ends can be pushed down through

RAMPS cam split end together as hanger is

pushed into slot Ends spread again when

notches engage sheet

Small end enters large slot first, then tilts over into smaller, close-fitting slot

Creative Assemblies 27- 19

LOOP hooks over bar and is held secure by

short tail which snaps into hole drilled

through the side

COIL grips edges of T- or I-section or flat

bar Spreading the ends wraps wire tightly

around tubing to prevent vibration

DOUBLE HANGER supports two tubes 8s

they pass through divider While tubes are in place hanger can’t come out

8 END PIECE supports pipe between waUs of

any thickness First spring it over pipe, then slide it along pipe into holes

SQUEEZE CLIP holds two overlapping

sheets together The ends of the clip are

pushed through parallel slots, then bent

over much like a staple

ALIGNING PIECE slides up out of the way in long slot while butting sheets are

being positioned Afterwards it slips down over lower sheet

CUP carries a bar on both sides of divider Here bars stick up above the top, but

deeper cutout will lower them until they are flush or sunk

ESS supports shelf between uprights, By

mating with notched edge it acts as a key

to keep shelf from sliding back and forth

and provides positive location,

RADIALLY ARRANGED DETENT HOLDS IN

SLOTTED INDEX BASE

27-22

SENSITIVITY OF BALANCE is

independent of temperature fluctua-

tions To keep the center of gravity

constant, two temperature-sensitive

elements are riveted to aluminum-

alloy balance beam, bridging a slot

which is directly over the balance

point Their coefficient of expansion

compensates for beam deflection

caused by variations in temperature

Enclosed in a cylindrical canister

at the rear of the balance beam is a

vane that damps its movement, pre- venting oscillation The hanger at the front of the scale carries sets of ring weights which are lifted by cam- operated levers The shafts on which the cams are mounted are connected

to the mechanical readout

The scale in effect weighs by sub-

traction since it is balanced, when empty, by all the ring weights resting

on the hanger To weigh an unknown, the ring weights are lifted from the hanger The sum of the raised weights

is shown on the mechanical counter,

which displays the first three digits

The complete total is displayed by the mechanical plus the optical system that projects through the reticle

Creative Assemblies 27-23

Warren Ogren, Inventor

Robert Parrnley, Draftsman

Exploded drawing of engine illustrates the many standard mechanical components that are arranged to preform a function in a new way

I L L U S T R A T E D S O U R C E B O O K of M E C H A N I C A L C O M P O N E N T S

DESIGN

Design Formulas 28-3

or

OLUME equations are included for ail cases Where

V the equation for the CG (center of gravity) is not

given, you can easily obtain it by looking up the volume

and C G equations for portions of the shape and then

combining values For example, for the shape above,

use the equations for a cylinder, Fig 1, and a truncated

cylinder, Fig 10 (subscripts C and T , respectively, in the

equations below) Hence taking moments

In the equations to follow, angle B can be either in

degrees or in radians Thus B (rad) = d/180 (deg) =

0.01745 B (deg) For example, if 0 = 30 deg in Case 3,

then sin 0 = 0.5 and

(volume of junction box)

20 .Intersecting hollow cylinders

(volume of junction box)

28-6

Design Formulas 28-7

29 .Shell of spherical sector

30 .Shell of spherical segment

31 .Circular hole through sphere

32 .Circular hole through hollow sphere

28-8

Design Formulas 28-9

circles aie tangent; points in lower right or left portions indicate one cir- cle is completely within the other

To Find Trne Angle:

These 5 scales show the most likely comhinationa of tipturn angles In each combi-

nation use the black d e for the case angle A Example: tip-turn angles are 5 O ; the

case angle is 2 9 O On shaded scale opposite 29", read that 20' must he added io get

true angle T = 29O20'

28- 14

Angle '8'

Graphical Solution of True Angle

This chart is laid out with two curves for tip-turn angle combi- nations Example: case angle A

1 29", tip and turn angles are 5" Follow construction lines to

see that 20' must be added to an- gle A = 29", to get true angle

T = 29"20'

Proof Given 0, a and @

To Find T

Solution:

AC = 1 = AB'

CB = tan o = B'C B'C' = sin + = CD B'C" = COS a (B'C + CE)

CE = tan a CD B'C" = (tan 0 + t a n a sin 9 ) X

LWS C = - cos A cos R + sin A sin B cos e (1)

This formula can be modified for logarithmic cornputntioo

by the use of an auxiliary angle x

(3) sin ( A - 2) cos B

(5) sin c sin 13

sin C sin b =

sin + = sin b sin A = sin a sin I3

tanm = t a n b cos A tan n = tan a cos I3

cot = tan A cos b

cot 8 = tan B cos a

Table I-Sign Convention for Trigonometric Functions

( I )

(11) (I 11) tan m

many difficulties as are likely to occur in practice Below

is given the computation of the angles pertaining to thc intersection of the sides M and N of the hopper The lower horizontal plane is taken as the plane of reference The pitch angles A and B are first computed from the given

d imensions ,

Angles, deg I sin cos tan cot sec csc

41 625 tan B = 28.814 -

Design Formulas 28-17

M and N is found from Eqs ( 2 ) and (3) :

Since log tan (1:) = 0 1597416 and log cos (c) = 9.8494550,

Next, the angles n and b at which thc sides A I and h

must be cut are found by Eqs (4) and ( 5 ) :

log sin a = 9.974543 1

log sin b = 0.8969296

u = 109' 25' 36"

b = 52" 4' 2"

T o check, use Eqs ( I ) , and (111), first finding

$ ( A + B ) and + ( A - B ) by addition and subtraction:

Therefore log cos+(a + b ) = 9 2LOW731,

log sec$(a - b) = 0 06G8439, aiirl

of the hopper, can be determined by a similar process The dihedral angle formed by the intersection of the sides N and P are:

The cut angles for the sides N and P are:

The pitch angle for the side P is 63" 55' 7" (See Fig 3 )

When the slopes of the sides M and N, and hence a and

b are equal, and c = 90°, the required equations then become :

Design Formulas 28-2 1

Oscillating welghi IW,)

4-Pendulum (connecting-rod weight relatively

light)

J = W,L (& - +)

Rod f W, J assume cross -section

5-Pendulum (connecting-rod weight appreciable)