ITEM #05739 Rev B
5
Drive Nut inspection:
General:
Because it is the main source of lift in the Genesis, the Drive nut is subject to a high
level of wear and must be checked regularly. Obvious signs of wear may occur in
extreme cases and may include, vibration, heat, creeping platform, deposits of the
plastic compound found in the bottom of the mast, or, in the most extreme case,
breakdown of the Nut causing the carriage to fall onto the Safety Nut. If any of these
conditions exist, the lift must not be used, and the worn components must be replaced.
Other signs
of wear may not be so easy to spot. However, it is important to closely
check the Drive Nut for wear. The following will help you identify potential problems.
Lift is creeping down.
This is a first indication that the Drive Nut is worn. A new Drive
Nut exerts pressure on the screw and will not allow the lift to creep. On older models,
tightening the Nut by turning the two Allen head bolts with a 10 mm Allen wrench will
prevent the lift from creeping. If this will not work or, if the creeping is excessive, the nut
must be replaced.
On more recent designs the drive nut is one piece and cannot be tightened. However,
because of the design of the more recent Drive Nuts, they are less likely to wear.
Drive Nut is worn.
With the platform close to the bottom floor, hand-crank the platform
downward slowly and observe the screw and Nut engagement. As the platform bottoms
out on the floor, you should not see the nut move relative to the screw. On older lifts,
another method to check this is to remove the backside of the Nut (it is in two parts) and
to bring it to a location where you engage it on the screw and observe how it seats into
the screw threads. It must fit with no vertical movement. If there is play, replace the nut.
Safety Nut and Safety Nut Switch inspection:
The causes and indications for Safety Nut wear are similar to the Drive Nut. The
Technician must look for anything that would indicate that the Safety Nut is loose or is
damaged. Look for shards of the distinctive bronze material the nut is made of in the
mast. You can check for play in the nut by reaching it with a screwdriver in its location
above the Drive Nut. By gently prying the screwdriver between the two nuts, you will
see if either nuts move. They must not! Any movement of one relative to the other,
means danger and the cause must be found.
The Safety Nut “floats” in its position above the Drive Nut. The two are separated by
springs on older models, but in BOTH older and more recent model lifts, they are
separated by at least one full turn of the screw. They are then retained in their location
so that the Safety Nut will never lock against the Drive Nut. The clearance between the
two is about 5mm or 3/16”. This can be checked visually. On the more recent Genesis
2006 lifts the gap between the two nuts is also occupied by a plate. The gap is then
measured between the top of the plate and the bottom of the Safety Nut.
