16
MAINTENANCE PROCEDURES
MAST MAINTENANCE
Essentially the mast is maintenance free. The mast sections run on
maintenance free rollers, and on the outer mast surface where the
roller runs, a brush is fitted to keep the mast surface clean, preventing
debris picking up in the roller. In addition to these rollers, there are
6 external plastic screws fitted, which act to hold the mast sections
together in torsion. These screws are fitted with M24 lock nuts and
can easily be identified at the lower end of the mast sections. Inside
the mast there are additional wear pads and rollers, which can be
accessed from the top of the mast. These items are not adjustable,
and it is very unlikely that any wear will occur.
The mast is raised and lowered with a multistage hydraulic piston,
which raises the outer mast section first, followed by the middle mast
section. When the mast is lowered, the sections close in the reverse
sequence i.e. the middle section and outer section close together
until the bottom of the middle section contacts the lower rest buffers,
and the outer section continues to close over the middle section. It is
essential the mast closes in this sequence.
To ensure the mast sections move in the correct sequence, and do
not bind, ensure the wear screws are not over tightened as follows.
Ensure the gap between the overlapping mast section and the inner
mast section is even on both sides. The distance is approximately
12mm, but may vary slightly due to manufacturing tolerances.
Loosen the wear screw lock nut and turn the screw until it just
contacts the inner mast surface. Do not force the screw. Tighten the
locknut using caution not to shear the screw thread. Raise and lower
the mast to check it does not bind. (See picture).
In practice, it is far more likely that the screws may wear so an
excessive gap between the mast section and the wear screw
develops. This will be evident by free sideways movement of the
platform. If this free movement is thought to be excessive, check the
gap between the screw and the mast with a feeler gauge. The correct
gap should be no more than 0.2mm, although the mast is serviceable
with a gap up to 0.5mm.
Mast wear screw adjustment
