JLG X23J - X700AJ Service Manual - Manual (Page 142)

SECTION 3 - CHASSIS & TURNTABLE
3121448 – JLG Lift – 3-115
POSITIONING THE SLEW DRIVE
1. Determine the main load-carrying zone. The main
load-carrying zone is that area of the slewing ring
that is subject to the highest load, taking all aggres-
sive forces and torques, and all occurring load
cases into account.
2. Arrange the hardness gap of the bearing ring
charged with point load so that it is offset by 90° rel-
ative to the main load-carrying zone. The main load-
carrying zone is in the main slewing range.
THE HARDNESS GAP OR THE FILLING PLUG IN A SLEWING RING
CONSTITUTE A ZONE OF DECREASED LOAD-CARRYING CAPAC-
ITY. THE SERVICE-LIFE OF THE SLEW DRIVE WILL BE REDUCED
SIGNIFICANTLY, IF THE HARDNESS GAP IS IN THE MAIN SLEW-
ING RANGE. FRACTURE OF BEARING RING FOR EXAMPLE MAY
CAUSE SLEW DRIVE FAILURE. CONSEQUENTLY PLACE THIS
MARKED POINT IN A REDUCED LOAD ZONE IF POSSIBLE.
3. Use a feeler gauge to check whether the support
surface of the slew drive is completely supported by
the mounting structure. If this is not the case, the
support surface of the mounting structure must be
reworked.
4.
Figure 3-193. Check the support surface
BOLTING THE SLEW DRIVE
DO NOT USE IMPACT SCREWDRIVERS. USING AN IMPACT
SCREWDRIVER MAY CAUSE IMPERMISSIBLE DEVIATIONS
BETWEEN THE BOLT TIGHTENING FORCES. FAILURE OF THE
BOLTED UNION WITH THE MOUNTING STRUCTURE MAY CAUSE
SEVERE PERSONAL INJURY OR MATERIAL DAMAGE.
MOUNT THE SLEW DRIVE IN UNSTRESSED STATE.
Strictly comply with the procedure specified below to
avoid impermissible deviations between the bolt tighten-
ing forces:
FIRST FASTEN THE HOUSING, THEN FASTEN THE
TOOTHED BEARING RING!
5. Lightly oil the bolt thread (not when using bolt lock-
ing devices with adhesive).
6. Pretension the bolts, with washers if required, cross-
wise in 3 steps, 30%, 80%, and 100% of the tighten-
ing torque, or the hydraulically applied pretension
force.
7. In this process turn the unscrewed ring several
times. Repeat the procedure for the bearing ring that
has not yet been bolted.
If using a hydraulic bolt-tensioning cylinder the tensioning
forces for the bolt pretension should not exceed 90% of
yield strength.
Figure 3-194. Tighten crosswise