| EXAMPLES:
A load
weighing 4 tons is pulled straight up. Observe how the TOTAL LOAD
on the block differs when the angle between the lead line and load
line changes. |
|
The truck
shown at right is lifting a 1000 lb. weight.
Load on block
A: 1,000 lbs. x .92 = 920 lbs.
Load on block
B: 1,000 lbs. x 1.77 = 1,770 lbs.
|
|
|
MATCH
WIRE ROPE OR FIBER ROPE TO SHEAVE. Using
rope of different size than the one for which the sheave is grooved
is potentially dangerous and will cause rapid wear of both sheave
and rope.
|
INSPECT
BLOCKS FREQUENTLY. Check
general condition of block components. Look for wear on sheave grooves,
sheave pins, wobble of sheave, security of bolts and nuts, etc. Make
sure sheave rotates freely and lubricate grease nipples frequently.
|
| BEWARE
THAT BENDING ROPE OVER SHEAVES WILL REDUCE ITS STRENGTH. The
smaller the ratio of sheave diameter to rope diameter the larger the
reduction in rope strength efficiency compared to the Catalog Breaking
Strength, and the more rapid the resulting wear on sheave and wire
rope fatigue. Avoid changing the bending direction from one sheave
to another, as this will rapidly accelerate rope fatigue. |
|
D:
sheave pitch diameter
|
|
d:
wire rope diameter |
|
