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Tackle Block Information

Tackle Block Maintenance

Tackle Blocks must be regularly inspected, lubricated, and maintained for peak efficiency and extended
usefulness. Their proper use and maintenance is equal in importance to other mechanical equipment. The frequency of inspection and lubrication is dependent upon frequency and periods of use, environmental conditions, and the user’s good judgment.

As a minimum, the following points should be considered:

  1. Wear on pins or axles, rope grooves, side plates, bushing or bearings, and fittings (See Fitting Maintenance). Excessive wear may be a cause to replace parts or remove block from service.
  2. Deformation in side plates, pins and axles, fitting attachment points, trunnions, etc. Deformation can be caused by abusive service and/or overload and may be a cause to remove block from service.
  3. Misalignment or wobble in sheaves.
  4. Security of nuts, bolts, and other locking methods, especially after reassembly following a tear down inspection. Original securing method should be used; e.g., staking, set screw, cotter pin, cap screw
  5. Pins retained by snap rings should be checked for missing or loose rings.
  6. Sheave pin nuts should be checked for proper positioning. Pins for tapered roller bearings should
    be tightened to remove all end play during sheave rotation. Pins for bronze bushings and straight roller bearings should have a running clearance of .031 inch per sheave of end play and should be adjusted accordingly.
  7. Hook or shackle to swivel case clearance is set at .031 to.062 at the factory. Increased clearance can result from component wear. Clearance exceeding .12 to .18 should necessitate disassembly and further inspection.
  8. Deformation or corrosion of hook and nut threads.
  9. Surface condition and deformation of hook (See Fitting Maintenance and ANSI B30.10.)
  10. Welded side plates for weld corrosion or weld cracking.
  11. Hook latch for deformation, proper fit and operation.

The frequency of lubrication depends upon frequency and period of product use as well as environmental conditions, which are contingent upon the user’s good judgment.
Assuming normal product use, the following schedule is suggested when using lithum-base grease of a
medium consistency

Sheave Bearings
Tapered Roller Bearings — Every 40 hours of continuous operation or every 30 days of intermittent operation.
Roller Bearings — Every 24 hours of continuous operation or every 14 days of intermittent operation.
Bronze Bushings — (Not Self Lubricated) — Every 8 hours of continuous operation or every 14 days of

Hook Bearings
Anti Friction — Every 14 days for frequent swiveling; every 45 days for infrequent swiveling.
Bronze Thrust Bushing or No Bearing — Every 16 hours for frequent swiveling; every 21 days for
infrequent swiveling.
Tackle Block Maintenance also depends upon proper block selection (see “Loads on Blocks”), proper reeving (see “The Reeving of Tackle Blocks”), consideration of shock loads, side loading, and other
adverse conditions

Sheave Bearing Application Information
Bronze Bushings —Bronze Bushings are used primarily for sheave applications using slow line speed, moderate load, and moderate use. The performance capability of a bearing is related to the bearing pressure and the bearing surface velocity by a relationship known as true PV (Maximum Pressure – Velocity Factor). The material properties of the Bronze Bushings furnished as standard in Crosby catalog sheaves are:
(BP) Maximum Bearing Pressure: 4500 PSI
(BV) Maximum Velocity at bearing: 1200 FPM
(PV) Maximum Pressure Velocity Factor: 55000
(It should be noted that due to material property relations, the maximum BP times the maximum BV is NOT equal to the maximum PV.)