Street Crane ZX6, Installation, Operation And Maintenance Instructions

Page: 29 / 103

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© Street Crane Co Ltd
Ref: D3256 rev. B Page 29 of 103
3.9 ULTIMATE UPPER LIMIT SWITCH – HOOK BLOCK OPERATED (OPTIONAL)
When specified, an ultimate upper limit may be fitted to the hoist unit to prevent the bottom block from
damaging the hoist should the normal upper limit switch fail. It should be set to activate at the upper level
given in section 3.10. The normal limit should then be set to activate approximately 75 ‐ 100mm below the
ultimate limit. A red warning light on the base of the control panel will illuminate to indicate when the second
ultimate limit has been activated.
Figure 19 – Ultimate Upper Limit Switch – Hook Block Type
3.9.1 Setting the ultimate upper limit
1
Extreme care must be exercised when testing the ultimate limit switch as it necessary to by ‐
pass the normal upper limit.

Reposition the normal upper limit such that the ultimate limit is the first to operate.

Raise the hook to the desired operating position at slow speed with no load attached allowing an
additional 50mm for a fast speed approach.
1
The upper hook level for low headroom hoists vary with the runway flange width. The hoist
will be seriously damaged if the hook is set higher than the values indicated in section 3.10.

Remove the bottom block trigger fixings such that the bottom block trigger can be split in two.

Position the bottom block trigger around the hoist rope.
1
The bottom block trigger must be positioned around the static rope on the reeving
arrangement i.e. the rope which passes over the Diverter sheave see Figure 19.

Replace block trigger fixings.

Adjust the length of the strainer wire and position of the bottom block trigger such that the limit switch
operates

Test the operating position in slow speed at first repeating the test in fast speed raising / lowering the
bottom block trigger where necessary.

Trim or secure any excess strainer wire.

Check that the red warning light in the base of the control panel illuminates.

Set the normal upper limit so that it operates approximately 75 ‐ 100mm below the ultimate upper limit
(see 3.6.2 ).