PowerPoint PresentationCourse name: B222 – Drive axle
Content: This module covers information about the drive axle of B222 units
General objectives: Familiarize students with the drive axle
Target Group: Big Truck technicians
Pre-requisites: The student should have a very good knowledge about hydraulic and mechanical systems and should be able to read and interpret hydraulic schematics.
Learning Objectives: Describe and locate the main components of the drive axle
Explain to level 2 technicians how the B222 drive axle works
Perform basic trouble shooting on the drive axle
Course Duration: 2 hours
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FINAL DRIVE
Pinion thrust washer
The planetary gear axle has an axle housing and two final drive assemblies. Each final drive assembly is a planetary gear unit.
The planetary gear assembly changes the final drive ratio, which increases the torque to the drive wheels.
Each unit has a drive axle, sun gear, ring gear hub, and ring gear. There are also three planetary pinions, a planetary spider, and a housing.
The differential is also installed in the axle housing.
The service brake is also installed on the drive axle. See the section Service Brake 1800 SRM1038 for repair instructions of the brakes.
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lift truck.
be removed:
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PLANETARY GEAR
Planetary carrier
Sun gear
Ring gear
Example: if Z sun = 11 T. & Z planet = 22 T. => R = 11 = 6 2 x (11+22)
Traditional equivalent ratio => 2 gears of 11 teeth & 66 teeth
Nbr of teeth of planetary gear = 11+22+22 = 55 T.
Nbr of teeth of traditional gear = 11+66 = 77 T.
(40 % difference)
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Remove cover from planetary gear carrier.
Remove planetary gear carrier cap screws.
Separate planetary gear
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remove planetary gear carrier.
press with flange side DOWN.
Press each pinion shaft out out.
Support the spider assembly as required.
NOTE: Use a soft material in bottom of the catch container to prevent damage to the pinion shafts Place a container under the press to catch the planetary pinion shafts as they are pressed out of the planetary gear carrier and planetary pinion gears.
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wheel bearing adjusting lock nut - bearing
adjusting lock nut (2) – and wheel bearing
adjusting nut (1)
of wheel hub and off of spindle.
Support the wheel hub before you remove ring gear and ring gear hub assembly. Do not remove ring gear and ring gear hub assembly without supporting the wheel hub. Serious injury and damage to components may occur.
NOTE: To avoid dropping and possibly damaging the outer wheel bearing cone, verify the outer wheel bearing cone remains in place as you remove the ring gear hub.
NOTE: If the ring gear hub cannot be removed by hand, install capscrews into the puller screw holes in the ring hub flange. Tighten each capscrew the same amount to separate ring gear hub from spindle and wheel hub.
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gear hub (1)
cover to the brake housing.
Carefully slide the brake assembly away
from the spindle using the lifting device.
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REMOVAL - Spindle
cap screws - Replace them with two
studs (1) and remove the remaining
capscrews.
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Park Brake knob
The inching brake pedal and the service brake pedal are connected mechanically with a common shaft.
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Lift the piston out of the housing.
The two piston seals and the seal spacer are removed with the piston.
Remove the stationary discs (1) and friction discs (2)
1
DISASSEMBLE - Brake piston springs
Spring (3) is held by the pin plug assembly (5) and the guide (hole type1)or (pin type 2). The O ring (4) should be replaced during maintenance.
Position into the housing
Use Press (6) to apply and keep pressure on the plug then loosen it slowly
6
6
The brake housing pressure must
remain at 7 bar (102 psi) for 3-5
minutes. If not,
water first. Without success,
Remove the wheel hub, inspect the spindle/hub seals for internal leaks.
Connect an auxiliary air supply system to the gauge and regulator assembly. Apply 7 bar (102 psi) of pressure to the brake
housing.
Turn the regulator to the CLOSED position. Look at the gauge for 3-5 minutes. The pressure in the brake housing must remain at 7 bar (102 psi).
If pressure falls below 7 bar (102 psi), find the cause of the loss of pressure.
Apply and hold 7 bar (102 psi) of pressure in the brake housing. If bubbles appear at any external location, service the cause of the leak.
If bubbles do not appear at any external location, there is an internal leak. Remove the wheel hub. Inspect the spindle to hub seal, face seal, and seal surface on the spindle for possible causes of leaks. Repair or replace as necessary.
Remove the plugs from the inlet and outlet ports. Remove the air pressure gauge and regulator assembly.
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BRAKE - System
Accumulator
Oil from the hydraulic pump goes to an accumulator charge valve to make sure the brake system has enough pressure to operate the brakes. See Hydraulic Schematic. A pressure switch connected to the brake circuit operates a warning light for the operator when brake pressure is low. The accumulator maintains the brake pressure and oil flow to brakes at each drive wheel. The system also supplies oil flow and pressure to operate the parking brake on the drive line near the differential.
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OIL COOLER
Xmsn Hydraulics Engine Charge air
The oil-to-air heat exchanger has cores stacked side to side. Cores are for engine cooler, charge air cooler, transmission cooler and hydraulic cooler. The engine cooling fan provides air flow. In case of a cooler failure, each section can be replaced individually.
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Description and Operation
The hydraulic system maintains a permanent charge of the accumulator through the variable flow hydraulic pump to operate the brake system.
Oil pressure from the accumulator is supplied to the brake treadle. The right-hand pedal only activates the service brakes. The left hand inching pedal first activates an electrical signal, and via the APC 200 controller, will fully disengage the transmission. The service brakes will then be activated. Both pedals will engage the brake pressure switch to operate the stop lights.
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This circuit is included and described in the hydraulic module
The charging system is part of the general hydraulic system. Please refer to the hydraulic module to check the new charging system of the accumulator.
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Cooling Circuit
Oil flows through the thermostatic bypass valve to the service brakes at each drive wheel. If the oil is above 70 C (158 F), the valve will direct the oil through the air-to-oil heat exchanger before it goes to the brakes. A check valve keeps the pressure in the brake assemblies to less than 140 kPa (20 psi). Oil from the brakes returns through a filter (20 micron), with a 35 kPa (5 psi) bypass, to the hydraulic tank.
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BRAKE PEDAL
16MPa (2321 psi maximum to packs
Oil pressure from the accumulator is supplied to the brake treadle. The right-hand pedal only activates the service brakes. The left hand inching pedal first activates an electrical signal, and via the APC 200 controller, will fully disengage the transmission. The service brakes will then be activated.
The left hand pedal is the inching pedal. Both pedals will engage the brake pressure switch to operate the stop lights.
Service brake and service brake treadle pressures are mesured at MSB1 and MSB4:
Service Brake (MSB1) =>17.0 to 17.5 MPa (2466 to 2538 psi)
Service Brake Treadle (MSB4)=>Maximum 16 MPa (2320 psi)
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Thermal Bypass Valve
1. Brake filter
2. Transmission filters
Brake cooling oil is filtered from friction material in the return line to tank. Filter has a bypass function, an indicator for filter element service, and a pressure switch connected to a warning light for filter element service.
Brake filter (20 micron). The brake filter is located inside the frame on the right hand side. The brake filter is filtering the return line from the cooling chamber of the brakes.
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Brake System
Brake Return Line Oil Filter
Check hydraulic oil pressure at check port MRF at full throttle and
maximum lowering speed and at minimum oil temperature 60 C (140 F).
If value measured is higher than 250 kPa (36 psi) => change filters.
Brake cooling oil is filtered from friction material in the return line to tank. Filter has a bypass function, an indicator for filter element service, and a pressure switch connected to a warning light for filter element service.
Brake filter (20 micron). The brake filter is located inside the frame on the right hand side. The brake filter is filtering the return line from the cooling chamber of the brakes.
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Brake pedal valve
The brake pedal and inching pedal are coupled, and activate one brake valve. When one of the pedals is depressed, hydraulic oil flows through the pedal valve to the service brakes. When the inching pedal is depressed, an electrical signal is also sent to the transmission controller to disengage the transmission. This allows high engine rpm lifting while braking, during stack approach.
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Park Brake
Brake Lining
When hydraulic pressure is released, the wave washer springs inside the brake expand to force the piston and linings against the disc. To release the brake, hydraulic pressure must be applied to release the springs. The brake can be released manually if hydraulic pressure is not available. Turn the cap screw down to cage the springs.
The operation of the parking brake is controlled by a solenoid valve for the parking brake. The solenoid is operated by a switch on the instrument panel. The solenoid is normally energized during operation for oil pressure to compress the spring to release the parking brake.
Parking Brake
NOTE: The parking brake, when in good condition and correctly adjusted, will hold a lift truck with a capacity load on a 15% grade [a slope that increases 1.5 m in 10 m (4.9 ft in 32.8 ft)].
NOTE: Always apply the parking brake when the truck is parked. A parking brake that is not applied will drain the batteries.Check the operation of the parking brake. The parking brake must apply when the knob for the parking brake is pulled. The parking brake must release when the knob is pushed.
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Pre-charge pressure 10.35 Mpa (1500 psi)
Pre-charge pressure which indicates possible failure of seals: 7.7 Mpa (1118 psi).
The accumulator provides pressurized hydraulic oil for the pilot system and/or the operation of the brakes by compressing pressurized nitrogen gas separated from the hydraulic oil by a piston. Without power, each brake application moves the piston in the accumulator incrementally to the left. There is hydraulic pressure to apply the brakes. When the accumulator piston bottoms at the left end of the accumulator, there is no more hydraulic pressure and, therefore, braking action stops. The pressure in the hydraulic system immediately before the piston bottoms is the nitrogen pre-charge pressure.
During service, the pre charge pressure will decrease as a result of the natural diffusion of nitrogen gas. Therefore the pre charge pressure must be checked every 6 months and recharged if required.
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Accumulator Inspection
Discharge time due
to internal leakage
Whenever around the truck while it is idling, listen for the charge cycle of the accumulator.
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Apply the brake pedal repeatedly and observe the gauge reading.
Repeat this procedure until a sudden sharp decrease in accumulator pressure is observed (the piston has bottomed).
The reading just before the sharp drop in pressure represents the pre-charge of the accumulator.
Refill with nitrogen gas at approximately 20 °C (68 F) to the required
pre-charge pressure => 10.35 Mpa (1500 psi)
The pre-charge pressure which Indicates a possible failure of seals
=> 7.7 Mpa (1118 psi).
Oil to brakes & Cooler out
Oil from pump
Cooler in
Brake cooling oil flows through the thermostatic bypass valve to the service brakes at each drive wheel. When the oil is hot, the valve will direct the oil through the air-to-oil heat exchanger before it goes to the brakes.
The valve is modulating valve regulated by a bimetallic strip. This strip contains two different materials with different expansion coefficients.
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Check Valve
Check Valve (140 kPa, 20 psi)
A check valve is installed in the brake cooling circuit to protect wheel end brakes against high oil pressure during cold conditions. When the check valve opens, it dumps excess oil to tank. The brake cooling chamber has a strict pressure limit to prevent face seal leakage @ brake housing – wheel hub interface, or hub seal leakage, causing the differential housing to fill with oil.
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Hydraulic system oil 605 L. (160 gal) => SAE J20C spec.
Transmission 62 L. (16 gal) => SAE 10W, API CC or CC/SE. Dexron III.
Drive Axle and Differential 65 L. (17.2 gal) => AE 80W-90 or 85W-140.
Spreader Rotator Transmission Oil SAE 80W-90 API GL5
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