Front Suspension Arrangement
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| Illustration 1 | g00649716 |
Front suspension arrangement (1) Cylinder mounting pin (2) Suspension cylinder (3) Front frame (4) Pivot pin cap for cradle (5) (5) Cradle (6) Axle case (7) Cylinder mounting pin | |
The front axle is mounted on a pivoting cradle assembly. Cradle (5) is bolted to axle case (6), and cradle (5) is attached to the main frame (3) by pivot pins (4) which are mounted in spherical bearings. This arrangement allows vertical movement of the axle. This arrangement does not allow vertical movement of one wheel relative to the other wheel. The cradle is a rigid assembly.
Suspension cylinders (2) are mounted between cradle (5) and the main frame (3) by pins (1, 7). Suspension cylinders (2) are connected to a nitrogen charged accumulator. The accumulator acts as a spring.
Rear Suspension Arrangement
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| Illustration 2 | g00649743 |
Rear suspension arrangement (1) Pivot pin (2) Rear frame (3) Suspension cylinder (4) Suspension cylinder (5) Rear axle (6) Rear axle A-frame (7) Pivot pin (8) Center axle (9) Center axle A-frame | |
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| Illustration 3 | g00649745 |
Rear view (2) Rear frame (5) Rear axle (10) Panhard rod | |
Center axle (8) and rear axle (5) are mounted on suspension A-frames (6, 9), which are attached to rear frame (2) by pivot pins (1,7) .
Pivot pins (6, 9) are mounted in spherical bearings in order to allow the axles to move vertically and pivot pins (6, 9) allow the suspension A-frames to tilt sideways. Each suspension A-frame is located laterally by a panhard rod (10) in order to prevent sideways movement.
Suspension cylinders (3, 4) are mounted between the rear frame and the suspension A-frames. Suspension cylinders are connected by a closed hydraulic system. The suspension cylinders on each side of the machine are connected together in a separate closed circuit.
If the center axle is deflected upward, oil from the front suspension cylinders is forced into the rear suspension cylinders and the rear axle moves down.
If one side of the center axle is deflected upward, the center A-frame will be tilted and the oil from the suspension cylinder on that side of the axle will be forced into the corresponding rear suspension cylinder. This would cause that side of the rear A-frame to be deflected downward.
Suspension Hydraulic System
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| Illustration 4 | g00649749 |
Suspension hydraulic system (1) Front suspension cylinders (2) Shutoff valve (3) Check valve (4) Suspension accumulator (5) Right rear shutoff valve (6) Right rear suspension cylinders (7) Bleeder valve (8) Left rear shutoff valve (9) Bleeder valve (10) Left rear suspension cylinders (11) Drain valve and fitting (12) Connection to the brake accumulators (13) Pump | |
The suspension system operates as three separate systems. The front system consists of suspension cylinders (1) and suspension accumulator (4). The right rear system consists of suspension cylinders (6) and the left rear system consists of suspension cylinders (10). The two rear systems are isolated by shutoff valves (5, 8) which are normally closed. These shutoff valves form a connection between the systems for servicing purposes only.
All systems are initially filled with hydraulic oil by pump (13) through shutoff valve (2) and check valve (3) .
Bleeder valves (7, 9) are intended for purging the rear systems as part of the routine servicing schedule. The front system and the rear system can be fully lowered by draining oil externally through shutoff valve (11). This can be done after you open shutoff valves (5, 8) .
Front Suspension Hydraulic System
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| Illustration 5 | g00649751 |
Front suspension hydraulic system (1) Front suspension cylinders (2) Restrictor check valve (3) Suspension accumulator (4) Piston | |
When the machine is unloaded, the piston rods of suspension cylinders (1) are extended past the midstroke position. When the machine is loaded, the additional weight moves the piston rods further into the suspension cylinders. This forces oil from the suspension cylinders into suspension accumulator (3). This raises accumulator piston (4), which increases the nitrogen pressure.
When the machine is moving, the suspension cradle pivots as the road wheels follow the contours of the ground. The piston rods move continually on either side of the midstroke position and oil flows in and out of the accumulator.
The nitrogen gas in the accumulator acts as a spring. The nitrogen gas compresses in order to absorb the road shock as the oil is forced into the accumulators by the suspension cylinders. The nitrogen gas expands as the suspension cylinders move back to the midstroke position.
As the cradle is deflected upward, oil from the suspension cylinders has full flow into the accumulator through restrictor check valve (2). This allows rapid upward movement of the axle in order to minimize the movement of the main frame.
When the piston rods are moving out of the suspension cylinders, the oil flow is controlled as the oil passes through the restrictor. This slows the rebound of the suspension cylinders in order to minimize bouncing of the suspension.
Rear Suspension Hydraulic System
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| Illustration 6 | g00649752 |
Rear suspension hydraulic system (1) Shutoff valves (2) Center suspension cylinders (3) Bleeder valves (4) Rear suspension cylinders | |
Shutoff valves (1) are normally closed and the suspension cylinders on the left side of the machine operate independently of the suspension cylinders on the right side of the machine.
Shutoff valves (1) are used in order to charge the rear suspension hydraulic systems.
The systems operate by transferring oil between the cylinders of each pair of suspension cylinders. This is done as the axles follow the contours of the ground.
Bleeder valves (3) allow the systems to be purged of air or oil. Oil is trapped in the rear hydraulic circuits and the oil can become dirty due to operating temperatures. Therefore, the oil is replaced as a routine service procedure. See Operation and Maintenance Manual, SEBU6904 for the full details of the procedure.
Bleeder valves (3) are used for venting the systems of air when you set the ride height after repairs. Bleeder valves (3) are also used to drain oil from the rear suspension systems.