Chains Flashcards
0
Q
Power transmission chain
A
- used as a positive drive to transmit power between widely spaced shafts
- 98% efficient
1
Q
Number one reason for chain wear?
A
-lubrication
2
Q
Two types of Pre-lubricated chain
A
- sintered bushing
- o ring
3
Q
Sintered bushing
A
- Bushings are charged with lubricant that is squeezed out when chain is under load
- has no roller
- lasts 5 times longer
- 10% less loading capacity than standard chain
4
Q
O-ring
A
- intended to provide lifetime lubrication and to exclude contaminants. 10 times cleaner than without for food places
- stronger than standard chain but 5% less than sintered
5
Q
Oilfield chain
A
- multiple strand chain that is made to ANSI dimensions and upgraded to API standards
- uses press fit instead of slip fit
6
Q
Types of chain
A
- roller
- silent
7
Q
Roller less chain
A
- designation #5
- run in sheaves instead of sprockets
- maintain tension where there is no or very little movement
8
Q
Silent chain (timing chain)
A
- Consists of links made up of tooth side plates
- highest efficiency
- high speed
- widest range of speeds
- widest range of load
- compact
9
Q
3 silent chain designs
A
- side guide
- centre guide
- duplex/serpentine drive
10
Q
What tools do you need for sprocket alignment
A
-straight edge and feeler gauge
11
Q
Chain wrap
A
-chain climbing up the back of the sprocket caused by too little tension
12
Q
Appropriate chain tension
A
- slow to med 4-6% sag
- high speed or vertical drive 2-3% sag
13
Q
Double Pitch
A
- same as standard chain but the pitch is double.
- used for long spans and low speed, low horsepower
14
Q
Master Clip installation
A
- closed end in the direction of travel
- remember trailing edge (end with split) is the back edge
15
Q
slip fit side plate
A
-reduces the working capacity of the chain by 30%
16
Q
press fit side plates
A
-do not reduce working capacity
17
Q
Too much chain tension
A
- will prevent lubrication from getting all around the shaft
- put undo pressure on the shafts, etc…
18
Q
Chain lubrication
A
- apply to inside of slack span
- low speed drives (under 600 ft per min) use manual or drip feed
- chains at 1500 ft per min use bath lubrication
- forced (oil pump from above)
19
Q
Elongation
A
-over 3% and the chain should be changed
20
Q
Galled
A
-Metal has been torn away from the surface of the pin
21
Q
Backstop
A
- restraining device that prevents the load from turning the drive when the drive is shut off.
- one way clutch is often used
22
Q
Minimum chain wrap angle
A
-120 degrees
23
Q
Double strand chain
A
- 1.7 times stronger than single strand
- side plates are press fit, but centre plates are slip fit
- higher load and speed capacity
24
Heavy Duty
- does NOT have a higher load capacity, but lets it last longer
- has thicker side plates
25
Single pitch offset link (half link)
- reduces the length of the chain by one pitch
| - consists of two bent side bars that are riveted to a bush and roller at one end
26
Most common light duty chain
- #41
| - has 1/4 wide rollers
27
Hunting Link
- used when an odd number of pitches is required
| - offset link
28
Joining pin or connecting link
- used to change the chain length by two pitches
| - convenient for assembling the chain in the field
29
Chain Length
- 1/2 the total sprockets times the pitch which represents the length the chain will wrap around the sprockets
- then double the drive centre distance.
30
To order new sprockets
-you need to provide chain pitch, chain type, number of strands and hub style
31
Bushing Failure
- Caused by overload
- sprockets too small
- imperfect form on the sprocket teeth
- badly worn or oversized gullet on the sprocket teeth
32
Roller Failure
-Caused when the sprocket repeatedly engages the sprocket teeth under load
33
Stretch
- One way a chain can be elongated
| - could jump off the sprocket
34
Pin Failure
- From constant flexing of the pin as each chain link moves over the sprocket.
- exposure to corrosives
35
Side Bar Failure
-Repeated stressing and unstressing of the chain as the links moved from the loaded and unloaded strands
36
Ways to improve service life on driver to driven
- increase centre distance
| - change the speed in two steps using a jack shaft
37
Idler Sprockets
- used as chain tensioner
- to prevent chain whip
- improve chain wrap
- to provide reverse rotation of a sprocket outside the chain
38
Idler Sprockets mount?
-on the slack span to reduce wear on the chain and sprockets
39
Hub Style A
-flat sprocket that can mount on any hub
40
Hub Style B
-Hub on one side
41
Hub Style C
-hub on both sides
42
Hub Style D
-split in the middle so you can mount it between bearings without having to remove them.
43
Sheer Pin Hub
- Provides the sprocket drive with overload protection in case of a jam
- shears off with too much force
- Uses Type A sprocket
44
Sprocket
-toothed wheel designed to mesh with power transmission chains
45
Installing sprocket
-there should be .002-.005 clearance between the top of the key and the sprocket
-none on the sides (some applications allow .002
-
46
Sprocket runout
-.002
