JLG M4069 ANSI Service Manual - Manual (Page 59)

SECTION 3 - CHASSIS & SCISSOR ARMS
3121122 – JLG Lift – 3-31
Roll Test
The purpose of the roll test is to determine if the unit’s
gears are rotating freely and properly. You should be able
to rotate the gears in your unit by applying constant force
to the roll checker. If you feel more drag in the gears only
at certain points, then the gears are not rolling freely and
should be examined for improper installation or defects.
Some gear packages roll with more difficulty than others.
Do not be concerned if the gears in your unit seem to roll
hard as long as they roll with consistency.
Leak Test (Main Unit)
The purpose of a leak test is to make sure the unit is air
tight. You can tell if your unit has a leak if the pressure
gauge reading on your leak checking fitting starts to fall
after the unit has been pressurized and allowed to equal-
ize. Leaks will most likely occur at the pipe plugs, the main
seal or wherever o-rings or gaskets are located. The exact
location of a leak can usually be detected by brushing a
soap and water solution around the main seal and where
the o-rings or gaskets meet on the exterior of the unit, then
checking for air bubbles. If a leak is detected in a seal, o-
ring or gasket, the part must be replaced, and the unit
rechecked. Leak test at 10 psi for 20 minutes.
Tightening and Torquing Bolts
If an air impact wrench is used to tighten bolts, extreme
care should be taken to ensure theat the bolts are not
tightened beyond their specified torque.
The following steps describe how to tighten and torque
bolts or socket head cap screws in a bolt circle.
1. Tighten (but do not torque) bolt "A" until snug.
2. Go to the opposite side of the botl circle and tighen
bolt "B" until equally snug.
3. Crisscross around the bolt circle and tighen remain-
ing bolts.
4. Now use a torque wrench to apply a specified
torque to bolt "A".
5. Using the same sequence, crisscross around the
bolt circle and apply an equal torque to the remain-
ing bolts.
Figure 3-18. Bolt Torquing Sequence