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| Illustration 1 | g01229055 |
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Position of the Ride Control Valve in the Loader Frame (1) Ride Control Valve (2) Ride Control Accumulator | |
Ride control accumulator (2) is located at the articulation joint on the right side of the front-end frame. The accumulator (2) contains a precharge of nitrogen gas. Ride control valve (1) will control the flow of oil between the ride control accumulator and the lift cylinders.
When the ride control system is activated and the machine travels over rough terrain with a loaded implement, the forces of the load act against the lift cylinders. When the load acts against the head end of the lift cylinders, oil from the head end will try to flow into the accumulator. The accumulator will act as a shock absorber.
Reference: For a schematic of the complete implement system, refer to Systems Operation, "General Information".
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| Illustration 2 | g01195410 |
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Ride Control Valve (Cross section view) and Schematic of the Ride Control System (2) Ride Control Accumulator (3) Lift Cylinder (4) Solenoid Valve Group (Rod End) (5) Solenoid Valve (Head End) (6) Check valve (two port cartridge) (7) Relief Valve (Ride Control) (8) Solenoid Valve (On/Off control) (9) Shuttle Valve (Balance) (10) Check Valve (11) Load Signal Resolver Valve (12) ECM | |
Note: Load signal resolver valve (11) is not used in the Ride Control System.
The ride control system is made up of the following components: lift cylinders (3), ride control accumulator (2), ride control solenoid valve (8), shuttle valve (9), head end solenoid valve (5), head end check valve (6) and rod end solenoid valve (4).
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| Illustration 3 | g01200595 |
| (13) Ride control switch | |
The ride control system is controlled by ride control switch (13). The ride control switch is a three-position switch that is located on the right side control panel in the cab. The three positions of the ride control switch are OFF, AUTO, and SERVICE.
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| Illustration 4 | g01195541 |
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Cab screen (14) Indicator Light (ride control) | |
Indicator light (14) will be illuminated when Ride Control is ON.
When the key start switch is in the ON position and the ride control is in the OFF position, ride control solenoid valve (8) is actuated. The valve spool in solenoid valve (8) shifts to the left. Head end solenoid valve (5) and rod end solenoid valve (4) are not actuated. In this position, the flow of the oil from the accumulator to the valve spool of shuttle valve (9) is blocked. This also prevents the oil from the head end of lift cylinders (3) from flowing to accumulator (2) which may eventually cause damage to the components of the ride control system.
The oil pressure in the head end of the lift cylinders will move the spool in shuttle valve (9) to the right. Pump supply oil flows to check valve (10). Check valve (10) opens and the pump supply oil will fill accumulator (2).
When the key start switch is in the OFF position, solenoid valve (8) is de-energized and the spool in solenoid valve (8) is moved to the right. The oil pressure in accumulator (2) acts against the right end of the valve spool in shuttle valve (9).
If the oil pressure in the head end of the lift cylinders has decreased, the valve spool in shuttle valve (9) moves to the left. When the spool is moved to the left, the path of oil from accumulator (2) to the hydraulic tank is opened. The oil in accumulator (2) will flow to the hydraulic tank. The spool in shuttle valve (9) will stay to the left until the pressures on each end are equalized. The spool will be centered when the pressure between accumulator (2) and the head end of lift cylinders (3) is equal.
In order to initiate the automatic ride control, push in on the top of the ride control switch. Refer to Illustration 3 for the location of the ride control switch. When the ride control system is in AUTO position, indicator light (14) on the dashboard will be illuminated. Refer to Illustration 4.
In the AUTO position, the ride control system functions automatically when the machine's ground speed increases above approximately
When the ride control switch is in AUTO and the machine's ground speed increases above approximately
The oil pressure in the head end of the lift cylinders acts as pilot pressure on the left side of shuttle valve (9). If the head end pressure is greater than the accumulator pressure, the spool will move to the right. When the spool is in this position, the supply oil from the hydraulic pump flows through check valve (10) in order to fill the accumulator.
The spool in shuttle valve (9) will move right to left and left to right in order to equalize the pressure between the head end of lift cylinders (3) and accumulator (2). When the pressure in accumulator (2) is equal to the pressure in the head end of lift cylinders (3), the valve spool for the shuttle valve (9) will be centered.
Note: The one second pressure equalization time for the ride control system is the default. The pressure equalization time can be changed through Caterpillar Electronic Technician.
After a one second pressure equalization time, solenoid valve (4) and solenoid valve (5) will energize. The valve spool in solenoid valve (5) will move to the left. In this position, pilot oil in the spring chamber of check valve (6) can flow back to the tank in order to allow the poppet of check valve (6) to raise.
When the valve poppet in check valve (6) is raised, the path of the oil between the head end of the lift cylinders and ride control accumulator (2) is open. The oil flow from the head end of the lift cylinders acts against the accumulator (2). Accumulator (2) works in the same manner as a shock absorber. Oil that is entering accumulator (2) is resisted by the nitrogen precharge in accumulator (2) and the forces of the work tool are dampened. This allows the accumulator to act as a dampener to the lift cylinders.
At the same time, solenoid valve (4) is energized. The oil from the rod end of the lift cylinders may flow back to the hydraulic tank. The hydraulic oil can flow from the tank line to the rod end of the lift cylinders (3) as makeup oil.
As the machine approaches the load site, the operator decreases the ground speed of the machine. When the ground speed goes below approximately
Note: The ride control activation speed of
No oil will flow from the lift cylinders to the ride control accumulator while the operator loads the work tool. This allows a greater breakout force for loading the work tool.
Note: If the work tool is loaded from an external source (a hopper or another machine) the pressure in the head end of the lift cylinders will increase. The operator must move the lift control lever to the RAISE position or the tilt control lever to the TILTBACK in order to create pressure in the implement hydraulic system. This will cause the implement pump to charge the accumulator.
After the bucket is filled and the operator increases the ground speed of the machine, the ride control system functions again. The pitching motion of the bucket is dampened.
Note: If the oil pressure in the head end of the lift cylinders is above the pressure of the ride control accumulator, oil will suddenly flow into the accumulator when the ride control system turns on. This will cause the lift arms to drop slightly.
Reference: For additional information about operating a machine with the ride control system, refer to Operation and Maintenance Manual, "Ride Control".
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| Illustration 5 | g01194315 |
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Technician Status Screen | |
Push in on the bottom of the ride control switch in order to put the ride control system in SERVICE mode.
Service mode is used for troubleshooting the ride control system. In SERVICE mode the ride control system will be ON at all times, except if the tilt valve status indicates that the DUMP solenoid is active. The ride control system is automatically turned off during a DUMP command to prevent loading of the lift cylinders and bucket jump up. The ride control will reactivate once an approximately 10 percent RAISE command is given.