ASME B29.8-2002 pdf download
ASME B29.8-2002 pdf download.LEAF CHAINS,CLEVISES, AND SHEAVES.
Maintaining a lubricant film on all chain surfaces should achieve the following:
(a) Minimize joint wear.
(b) Improve corrosion resistance.
(c) Reduce the possibility of pin turning.
(d) Minimize tight joints.
(e) Promote smooth, quiet chain action.
(f,J Lower chain tension by reducing internal friction in the chain system.
Laboratory wear tests show #40 oil to have greater ability to prevent wear than #10 oil. Generally, the heaviest (highest viscosity) oil that will penetrate the joint is best.
Whatever method is used, the oil must penetrate the chain joint to prevent wear. Applying oil to external surfaces will prevent rust, but oil must flow into the live bearing surfaces for maximum wear life.
To prepare the chain for oiling, the leaf chain plates should be brushed with a stiff brush or wire brush to clear the space between the plates so that oil may penetrate the live bearing area.
Oil may be applied with a narrow paint brush or directly poured on, but the chain should be well flooded to ensure that the oil penetrates into the joints.
In locations that are difficult to reach, it may be necessary to use a good-quality oil under pressure, such as an aerosol can or pump pressure spray.
A3 INSTALLATION
A3.1 Chain Movement
Ascertain that the chain operating path is clear and that the chain articulates freely through its full range of operation.
A3.2 Lubrication
Ensure that the chain is well lubricated with the heaviest oil that will penetrate the void between the link plate apertures and the pins.
A4.2 Inspection for Chain Damage
Each specific application should be evaluated, based on the degree of exposure and the areas of possible operation, and to prevent chain failure, a chain replacement schedule should he established. This schedule can he determined through inspection and the frequency of inspection can he changed, based on the observations. This inspection procedure should continue until a projected time of replacement can be predicted.
A chain by its very nature and exposure should be considered an expendable item. It is further recommended that chain exposed to very low temperatures or chain used in corrosive atmospheres receive frequent and very thorough inspection until a reliable replacement cycle can be determined and a safe chain replacement schedule can be established.
A5 DYNAMIC IMPULSE/SHOCK LOADS
The following are examples of dynamic shock loading that can impose abnormal loads above the endurance limit of leaf chain:
(a) high velocity movement of load, followed by sudden, abrupt stops;
(b) carrying loads in suspension over irregular surfaces such as railroad tracks, potholes, and rough terrain;
(c) attempting to “inch” loads that are beyond the rated capacity of the handling or lifting mechanism.
The above load cycles and environmental conditions make it impossible to predict chain life. It is therefore necessary to conduct frequent inspections until replacement life can be predicted.
A6 PERIODIC INSPECTION
After each 30 days of operation (more frequently in hostile environments), leaf chains should be inspected and lubricated. Inspection details are described in Table Al. The inspection should focus on the details described in suhparas. A6. I through A6.4.
A6.1 Elongation
When a theoretical length of 12.000 in. per foot of new chain has elongated from wear to a length of 12.360 in., it should be discarded and replaced. It is important to measure the chain in the section that moves over the sheaves because it receives the most frequent articulation. Measuring the chain near its clevis terminals could give an erroneous reading, for it would not have flexed there as frequently, if at all, as it would near the middle of the assembly.
