Chains Flashcards
Heavy duty chain is recommended for
Heavy shock loading and reversing drives
Heavy duty chain does not have higher load capacity but the thicker side plates increase its__________ thereby providing longer service life?
Resistance fatigue
Multiple strand chain is used in heavy loads and _______ applications
High speed
Double strand chain is approximately _______ time stronger the. Single strand
1.7 times
What is the difference between oil field chain and standard multiple strand chain?
Oil field chain is engineered for severe conditions.
Oilfield chain uses press for centre plates instead of slip fit. Making it stronger
Synthetic chain is up to ____ to ___ % lighter the. Steel chain
15 to 20
Where is a rollerless chain used?
Maintain tension where motion is infrequent or very slow.
Lift chain on counterweights
Furnace doors
Silent chain (timing chain) offers the ?
Highest efficiency
Widest range of speeds
Widest range of load capacities
Most compact design
A hunting link is used in silent chain when ?
An odd number of pitches is needed
Alignment in chain sprockets must be checked in both the horizontal and _______ planes.
Vertical
Slip fitted con link changes the chain length by 2 pitches. And reduces the working capacity of chain length by ______%
30
Do press fit con links reduce chain load strength?
No
Master links with spring clips must be installed in which direction?
Closed end of the spring clip facing the direction of travel
To much tension causes :
- reduced chain and sprocket life
- over loading of bearings
- inadequate lubrication
To little chain tension causes?
- chain whip and vibration which can destroy bearings
- excessive chain sagging
- chain wrap on sprockets
Chain sag percent for low to medium speed drives?
4 to 6 percent
Proper chain sag for high speed, reversing or impulse drives should be
2 - 3 %
Chain slack for vertical drives?
2-3%
Before approaching a running chain you must:
- ## remove any loose apparel or jewelry
What is the correct way to carry a chain?
What is the best way to control a chains wear?
Lubrication
Tips for proper lubrication and lubricating chains?
- good grade petroleum oil without additives (block entry of oil to pin and bushing)
- select oil with highest viscosity that still flows into the joint
- grease on outside of chain only provides corrosion resistance
- ensure lubricant is applied at the side plates
Chain lubrication for chains operating 1500 feet per minute?
Oil bath lubrication
Lubrication method for low speed drives under 600 feet per minute
Manual or drip feed lubrication
Forced lubrication is used on which drives?
Heavily loaded drives operating above the speed limits of bath lubrications
The aim of inspecting and troubleshooting chain drives is?
To make machines run as efficiently and as reliably as they did when they were new
Inspection of chain drives should include the following:
- inspect guard
- make sure guard fits entire drive
- make sure backstop is installed properly to prevent roll back
Lubrication checks
- low speed drive make sure lubrication schedule is followed
- remove dirt from chain and relubricate
- check drip lubricators for adequate flow
- check oil level for bath lubrication
- check for contamination in oil change if needed
- on forced lubrication check each orifice is clear and directing oil to each link
- check the chain tension and adjust as needed
- check for evidence of inadequate lubrication.
If chain is elongated by more the. ___% it needs to be replaced.
3
If rollers ride up on the tips of the sprocket what should you do?
Change chain
When checking sprockets for wear replace if any of these signs are present:
- roughness or binding when the chain engages
- teeth thinned down
- teeth hooked at the tips
If sprockets are showing west on the sides it is an indication of?
Misalignment
Why do you not install a new chain on a worn sprocket and vice versa?
Worn chain will wreck a new sprocket
Worn sprocket will wreck new chain
Bushing failure can be caused by overload however other causes are unique to bushing failure such as:
- sprockets that are to small
- imperfect form on the sprocket teeth
- badly worn or oversized gullet on the sprocket teeth
Chain designation chart
When ordering sprockets you must specify the :
- chain pitch
- chain type
- number of strands
- hub style
Large sprocket ratios will create a ______ wrap angle?
Small.
The closer the sprockets are and the longer the drive is the larger the wrap angle.
What is the ideal wrap angle?
120 degrees is ideal but as low as 90 degrees will still transmit the load.
Recommend drive arrangements. See picture
Idlers sprockets tension chains but also:
- prevent chain whip
- improve chain wrap on the smaller sprocket
- guide the chain away from obstructions
- provide reverse rotation of a sprocket outside the drive
When would you want hardened tooth sprockets?
- when number of teeth is 25 or less
- heavily loaded drives
- abrasive conditions
- high speed drives
- drives that require extremely long life
Type A hub
Flat plate style sprocket. Can have a hub bolted or welded on
B type sprocket hubs?
Hub on one side. Not as strong as both sides but still strong enough for the load.
Type C sprocket hub?
Hub on both sides. Good for large sprockets to provide support.
After a QD bushing has been installed there should be how much gap between the sprocket and the flange?
1/4 to 1/8 gap
Split taper bushings have alignment keys offset from the centreline. When installing multiple sprockets it is very important to ?
Make sure the tapers are all facing the same direction or the teeth won’t line up to the other sprockets
When installing a taper lock bushing you need to tighten the set screws progressively and evenly then _______ and retighten this step until screws remain tight.
Knock against sprocket with a soft faces hammer
