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 4.3.3 Overhead Beams And Fastenings
Examine overhead beams to determine whether they are securely fastened to supports or firmly
embedded in walls. Note any settlement of supports. Examine all exposed bolt fastenings of
beams supporting machinery or sheaves.
4.3.4 Overhead Grating Or Platforms
Determine whether any overhead grating or platform has openings of a size in excess of that
permitted by the Code. openings in bar type gratings must reject a ball 3/4 inch in diameter.
openings in fabricated openwork or perforated or expanded sheet metal must reject a ball 1 inch
in diameter.
4.3.5 Traction Driving sheave
4.3.5.1 Inspection Made with Power Off. open the mainline switch and proceed. Hammer-test
sheave and spider as previously described. Inspect fastenings for tightness where demountable
sheaves are attached to the sheave spider. Note any evidence of lost motion or misalignment of
the traction sheaves with other sheaves. Examine the traction sheaves for worn grooves and
determine that all ropes seat to the same depth in the grooves. (See Figures 2-9 and 2-10).
Particles of metal under rope sheaves are evidence of groove or sheave wear. Traction sheave
wear is usually just detected by finding metal particles under the sheave. However, an inspector
should watch for the signs that lead to wear before you see the results. The major cause of wear
is uneven rope tension. The sheave is designed to carry the load spread over all the ropes. When
one is under more tension than the others, this load is transferred to the tighter rope. This can
usually be seen by laying a straight edge across the ropes in the drive sheave grooves. All ropes
should touch the straight edge. Ropes that do not touch indicate uneven tension or possible
sheave wear. occasionally, an inspector will find a sheave with an unused groove or two.
However, most of the time it is not used by design, but it never hurts to check the cross head data
tag to verify. It is good practice to confirm the data for the actual rope size and construction.
occasionally, mistakes are found. Changes in the type or size of the specified hoist ropes will
change the rope to sheave traction factor resulting in either insufficient traction or excessive
traction. Either condition can result in dangerous consequences. Insufficient traction results in
the drive machine losing control of the car and counterweight. This could result in an
overhauling load from either side causing a run away condition. Too much traction could result
in the machine lifting either the car or counterweight if the other were to stop and the machine
continued to run. The traction factor is extremely critical to safe dumbwaiter operation.
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