Year 2 - 3Ca - Compressor Cylinder Components Part A

Front 1

What is another name for single acting compressor?

Back 1

Truncated or trunk style

Front 2

In a single acting compressor what does the piston attach to?

Back 2

Directly to the connecting rod

Front 3

What are throws?

Back 3

They are the attachment points of the connecting rods located on the crankshaft

Front 4

what are some advantages of having a cast iron piston?

Back 4

-they expand at the same rate as the cylinder

-can withstand high temperatures

-they don't wear very much

Front 5

when is a cast iron piston generally used?

Back 5

on large slow moving compressors

Front 6

when are aluminum pistons generally used?

Back 6

-they are commonly used on high speed reciprocating compressors to help with vibration caused by the inertia of the reciprocating parts.

-they may also be used to balance out the two stages so that weights are similar

Front 7

what lubrication method do smaller trunk style compressors use?

Back 7

the splash method, it both lubricates and cools off the compressor

Front 8

what is another name for a piston pin?

Back 8

wrist pin

Front 9

what are the 2 types of piston pins?

Back 9

1)full floating

2)semi-floating

Front 10

explain what a full floating piston pin is

Back 10

full floating pison pins are free to move inside both the con-rod bushing and the piston bushing. they are held with snap rings on either sides of the piston bore

Front 11

explain what a semi-floating piston pin is

Back 11

semi-floating piston pins can either be locked onto the connecting rod and free to move on the piston bushing or be locked to the piston and free to move in the con-rod bushing

Front 12

a double-acting compressors piston is connected to

Back 12

a piston rod that is then connected to the crosshead which connects to the con-rod

Front 13

rider bands support the weight of....

Back 13

the piston and half the weight of the piston rod

Front 14

what are a few different ways that a piston can be held onto the shaft?

Back 14

-against a shoulder with a nut

-tapered shaft and nut

-multiple bolts holding the piston parts onto a flanged piston rod

Front 15

what is rod runout?

Back 15

it is when the piston rod isn't running totally straight through the packing

Front 16

what is rod loading?

Back 16

rod loading can be either in compression or in tension

- compression occurs as the piston moves towards the head of the cyl, the force of the discharge pressure on the piston tends to buckle or bend the rod

-tension occurs when the piston is heading towards the crosshead and is under extreme pull pressures

Front 17

what problems can be caused by excessive rod loading?

Back 17

-damaged crosshead adn con-rod bushings

-frame failures

-valve problems

-broken or bent piston rods

Front 18

what is net compression?

Back 18

the difference between suction and discharge pressures

Front 19

what parts are most commonly affected by excessive rod loading?

Back 19

-the crosshead pin and bushing

-the con-rod bushing

Front 20

what is rod reversal?

Back 20

it refers to the reversal of the rod load from compression to tension. its a good thing. when the rod is in compression all the clearance on the crosshead pin is to one side allowing it to be lubricated, when it goes into tension the clearance is shifted to the opposite side of the bushing and can have its turn being lubricated

Front 21

what is a tail rod?

Back 21

a tail rod is a common method of compensating for lack of rod reversal by equalizing the surface area. it reduces the capacity of the compressor but is often necessary to ensure rod reversal

Front 22

if you need to grind out scratches on a rod, what is the rule of thumb for how much material you can remove?

Back 22

usually no more than 0.002" per inch of rod diameter if the original size packing rings are to be used again

Front 23

how you check is a shaft is straight?

Back 23

put it in v-blocks or between centers of a lathe. set up a dial in the center and spin the rod

Front 24

do oil rings exist on double acting compressors?

Back 24

no, only on trunk style compressors

Front 25

what are some benefits of using synthetic piston rings over cast iron?

Back 25

-they outlast cast iron rings

-better with abrasion, corrosion, and acidic gas

-soft enough they dont score the cyl

-almost no break in period

(cast iron rings are very cheap though)

Front 26

why is there an end gap on a compression ring?

Back 26

it allows for thermal expansion

Front 27

how does the compression ring seal?

Back 27

through a combination of cyl pressure, ring tension, and oil film

Front 28

what are the different types of piston ring joints?

Back 28

-butt joint

-angle joint

-step joint

Front 29

how do you check ring end gap?

Back 29

by placing the rings together in the cyl at the smallest ID. this may be at BDC for single acting or in the middle of the stroke for doubling acting compressors. (the high pressures tend to make a very slight buldge in the tube)

Front 30

what are the different types of rider bands?

Back 30

-uncut

-angle cut with a side relief groove

-angle cut with pressure relieved face and side grooves

-double twin ring rider ring

Front 31

in what situation do you need to use uncut rider rings?

Back 31

when they pass over a valve port

Front 32

in what situation do you nee to use the double twin ring rider ring?

Back 32

they are made for use on pistons that are to short to have separate grooves for the piston rings

Front 33

how are uncut rider rings installed?

Back 33

manufacturers can provide a rider ring pre-stretched and mounted on a carrier ring that fits over the piston

Front 34

how do you set the piston to cylinder head clearance?

Back 34

by turning the piston rod into or out of the crosshead and then locking it into place

Front 35

what is the general rule of thumb for setting the piston clearances?

Back 35

if the manufactureres specifications arent available you must set the crank end clearance at 1/3 and the head end clearance at 2/3 of the total. this accounts for thermal expansion

Front 36

what is a balance nut used for?

Back 36

they are used to fine tune the weight balancing of opposing multi-stage reciprocating compressor parts

Front 37

piston speed is constant while traveling from BDC to TDC. true or false?

Back 37

false. its depends on the angle of crank throw

Front 38

Card #38

Back 38

Finished