Axle Assemblies; Axle Assembly Description; Axle Assembly Operation; Axle Serial Number Plate - JLG sky trak mmv Service Manual

WARNING:
vehicle without following all safety precautions
as outlined in the "Safety Practices" section of
this manual. Failure to follow the safety prac-
tices may result in death or serious injury.
5.2

AXLE ASSEMBLIES

5.2.1

Axle Assembly Description

The front (parking-brake equipped) and rear (no parking
brake) ZF axles are designed for heavy-duty, off-road in-
dustrial use. Each axle consists of a beam-type axle
case, housing the differential center section, inboard wet-
disc brakes, a pair of trumpet-like shaft housings, and
stub-axle/wheel-hub units at each end. O-rings and oil
seals retain fluid within the axle. The axles have a semi-
floating mounting configuration. Each axle center is se-
cured to the vehicle frame with semi-rotating front and
rear supports, and at one side with a cylinder, anchor and
pins.
The frame sway cylinder is mounted on the right side of
the front axle and the stabilizer cylinder is mounted on the
left side of the rear axle. Steering cylinders and ball joints
are mounted inboard on each axle.
5.2.2

Axle Assembly Operation

Power from the engine is transmitted through the torque
converter and transmission, the transfer case by way of a
driveshaft. The transfer case distributes power through
the output drive shafts to the front and rear axle differen-
tials. The axles work through gearing to turn the wheel
and tire assemblies and to ultimately cause the vehicle to
move.
The front differential is equipped with limited-slip, self-
locking gears, supported by bearings. The design of the
differential permits adjustment to the bevel gear set. In-
ternal axle service and adjustment procedures are not the
scope of this publication and are thoroughly covered in
the appropriate ZF axle manual. The beveled ring gear is
adjusted by means of ring nuts located opposite each
other. The position of the pinion, supported by two bear-
ings, is adjusted through the addition or subtraction of ad-
justing shims.
The wheel hubs containing the planetary reduction gears
are supported by two tapered roller bearings. The oil-bath
(wet) disc type brakes are located in the center housing,
and are operated by an annular piston. The parking brake
is located in the center section of the front axle. The brake
is Spring Applied, Hydraulically Released (SAHR). The
parking brake uses the same discs as the service brakes.
Model MMV Rev. 12/04
DO NOT service the
Axles, Wheels and Tires
A double-rod hydraulic steering cylinder is mounted on
the differential support. Directional steering input is trans-
mitted to the axles by means of articulated track rods that
allow toe-in adjustments.
The axles are supported with two specially designed sup-
port trunnions (one at the front and one at the rear of each
axle), attached to the axle center and chassis. The trunnions
allow the axle to pivot freely, each limited by the hydraulic
cylinder attached to one of the bridge casting bearing lugs.
Note: Detailed axle service instructions (covering axle,
brakes and wheel-end safety, repair, disassembly, reas-
sembly, adjustment and troubleshooting information) are
provided in the ZF Axle Repair Manuals, Model MS-T
3060, front axle with parking brake (ZF part number
5871 560 002, JLG part number 8990430) or Model
MS-T 3045, rear axle without parking brake (ZF part
number 5871 550 002, JLG part number 8990419).
The MMV uses a wheel with nominal dimensions of 13" x
25". The wheels are a one-piece design with ten one-inch
diameter holes equally spaced on a 13.188" diameter bolt
circle.
An L2, 2 Star (or better) tire, 15.5R25 size, can be used
on the MMV. Tires are filled only with air when the vehicle
is shipped from the factory.
5.2.3

Axle Serial Number Plate

The front axle serial number plate (1) is located on a
mounting pad on the inboard portion of the right beam
trumpet. The rear axle serial number plate is located on a
mounting pad on the inboard portion of the left beam
trumpet. Information on the serial number plate is re-
quired in correspondence regarding the axle.
Supply information from the axle serial number plate
when communicating about an axle assembly or axle
components.
1
MT0220
5.3