Compressors - Cylinders

Question 0

What type of compressors use trunk type pistons?

Answer 0

Only single acting

Question 1

Where does the packing lubrication enter the cylinder and how is it circulated?

Answer 1

When the lubrication comes in from the top it is fed to the first and second sealing cup. It migrates to all the cups, etc… Through pressure and gravity

Question 2

What is the difference between a full floating piston pin and a semi floating?

Answer 2

Full are free to move inside both the con-rod bushing and the piston bushing. Semi are fixed to one of those two.

Question 3

How does an inter cooler improve efficiency?

Answer 3

• It lowers the temperature which improves lubrication

- lowers power required as well, heat is bad

Question 4

Packing rings

Answer 4

Pressure breaker
radial cut
tangent cut
anit-extrusion ring

Question 5

Pressure breaker

Answer 5

• first line if defense
• restricts pressure allowed to enter the packing case
• only ring used singly

Question 6

Radial cut

Answer 6

• always used in pairs with tangent cut

- lets some pressure through to help the other rings seal

Question 7

Tangent cut

Answer 7

-the main sealing in a two ring set

Question 8

Anti-extrusion (backup) ring

Answer 8

• doesn’t squeeze the rod so it can allow heat to escape

- helps keep the other rings in place

Question 9

Cooling packing cases

Answer 9

-it enters through the bottom of the packing case and out through the top

Question 10

What helps keep the piston riding true even if it sits a little low after installation?

Answer 10

Pressure compensation.

Question 11

What are the 3 main piston rings and what do they do?

Answer 11

Piston ring - seals
Rider band - supports
Rider ring - seals and supports half of the weight of the rod

Question 12

What are the requirements when cooling cylinders?

Answer 12

Air cool up to 88c
Liquid with no pump 88-121
Liquid with pump 121 or higher

Question 13

What is important to remember when measuring a cylinder bore?

Answer 13

Measure it in 3-4 places both vertically and horizontally

Question 14

What is the most common packing ring arrangement for low pressure systems?

Answer 14

One radial cut and one tangent cut. The radial ring faces the pressure in this situation with letters also facing the pressure side.

Question 15

What packing ring is only used singly?

Answer 15

A pressure ring

Question 16

What is the purpose of the oil wiper packing?

Answer 16

To prevent crankcase oil from passing along the rod into the cylinder.

Question 17

New cylinders are hydro tested to what pressure?

Answer 17

1 1/2 times the max allowable working pressure

Question 18

Where do we find oil wiper packing?

Answer 18

On the crank side of the distance piece from the full floating mechanical packing.

Question 19

What are anti-extrusion rings?

Answer 19

A backup ring with a radial cut with an OD larger than the rod. They conduct heat away from the rod because of their light contact

Question 20

Cylinder wear

Answer 20

If the clearance after a certain amount of time is more than the original clearance than you have wear on the ring and the cylinders. Think test question

Question 21

Rider bands

Answer 21

• prevent the piston from touching the cylinder during start up
• support the weight of the piston and half of the piston rod
• uncut are used when they pass over the valve ports or into the counterbore in the end of the cylinder

Question 22

Dry liners

Answer 22

• fits inside the machined bored and doesn’t touch the coolant
• press or interference fit

Question 23

Wet liners

Answer 23

• thicker than dry liner
• will contact the coolant and convection carries away the heat
• better for high pressure applications.

Question 23

Liquid cooling for the cylinder

Answer 23

• enters at the bottom and near the discharge valves

- exit at the top near the suction valve

Question 24

Radial/tangent packing ring

Answer 24

• Radial faces pressure side

- they are dowelled together with both sets of letters facing pressure side