Published 08-25-09, Control # 077-04 8-1
RT9130E SERVICE MANUAL UNDERCARRIAGE
SECTION 8
UNDERCARRIAGE
AXLES
Description
To provide maximum maneuverability, both the front and rear
axles are steerable. The rear axle is mounted on a pivoting
cradle (fifth wheel) which allows the axle to oscillate while
traversing uneven terrain. The front axle is bolted directly to
the frame. All four wheels utilize a hydraulic braking system.
Cranes are equipped with disc type brakes. A disc-type
parking brake is mounted of the front axle input shaft.
Each axle incorporates a single reduction carrier with hypoid
gearing mounted in the axle center. The final reduction is of
planetary design spur gearing built into the wheel hubs.
The design of these axles permits the hypoid gearing of the
differential carrier and the axle shafts to carry only a nominal
torsional load while at the same time providing the highest
practical numerical gear reduction at the wheels.
The hypoid pinion and differential assembly of the first
reduction are supported by tapered roller bearings. The
pinion bearing preload is adjusted and maintained by a
hardened precision spacer between the inner and outer
bearing. The differential tapered bearing preload is adjusted
and maintained by the positioning of the threaded adjusting
rings in the carrier leg and cap bores.
In the planetary wheel ends, the spur teeth of the sun gear
mesh with teeth of the planet spur gears. The planet spur
gears rotate on planet pins which are mounted in a spider.
The planet spur gear teeth in turn mesh with teeth of the
floating ring gear.
Power is transmitted by the hypoid gear set in the differential
carrier to the axle shafts and the sun gear of the final
reduction, through the revolving planet gears, and into the
planetary spider which drives the wheel hub.
As an option, the front axle and rear axle may be provided
with a differential lock. When in the locked mode, the axle
shafts and the differential are locked together and there is no
differential action between the wheels.
MAINTENANCE
NOTE: The axles do not have to be removed from the
crane to remove the planetary wheel ends or the
drive units.
Removal
1. Using the outriggers, raise the wheels off the ground.
2. Install blocking under the frame at the outboard ends of
the four outrigger boxes.
3. Disconnect and remove the drive line from the
applicable axle. Do not disassemble the drive lines.
Refer to DRIVE LINES in Section 7 - POWER TRAIN.
4. Tag, disconnect, and cap the hydraulic brake line at
each wheel.
5. Tag, disconnect, and cap the hydraulic lines to the steer
cylinders.
6. On the front axle only, tag and disconnect the hydraulic
line from the park brake actuator.
7. On the right side of the rear axle only, tag and disconnect
the electrical wires from the rear wheels not centered
switch.
8. On machines equipped with cross-axle differential locks
remove hoses and wires from the differentials.
NOTE: Each tire and wheel assembly weighs
approximately 1089 kg (2400 pounds).
9. Remove the wheels from the axle.
NOTE: Each axle weighs approximately 2750 kg (6050
pounds) with oil. Refer to Wheels And Tires in this
section.
10. Position jacks, which are capable of handling the weight
of the axle, under the axle for support.
11. Remove the eight nuts, washers, and bolts securing the
axle to the frame/cradle.
12. Lower the axle to the ground and remove it to a clean
working area.
13. If a new axle is to be installed, remove the following from
the old axle and install them on the new one.
a. The steer cylinders.
b. The rear wheels not centered switch actuator
bracket (rear axle only).
c. The parking brake actuator (front axle only). Refer
to BRAKE SYSTEM in this section.
CAUTION
Do not disassemble drive lines when removing them from
the crane. Dirt can enter the spline and cannot be purged.
In addition, the drive lines are assembled in a specific
orientation when manufactured and can easily be
incorrectly reassembled.
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