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| Illustration 1 | g06121886 |
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Left Rear Wall Inside Cab (1) Back-up alarm relay | |
Back-up alarm relay (1) is located in the fuse and relay bank. The panel in the left rear wall of the cab (shown removed) provides access to this component.
Back-up alarm relay (1) controls the power supply to the back-up alarm. When this relay is energized, the back-up alarm sounds. The machine ECM controls the signal to the coil of the back-up alarm relay. The machine ECM energizes this relay when the propulsion lever is in the reverse range.
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| Illustration 2 | g06121888 |
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Rear of Machine (2) Back-up alarm | |
Back-up alarm (2) is at the rear of the machine. The engine compartment cover provides access to this component.
Back-up alarm relay (1) controls the power supply to back-up alarm (2).
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| Illustration 3 | g06121890 |
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Under Operator Platform on Left Side of Machine (3) Shift solenoid | |
Shift solenoid (3) is on the left side of the machine, under the operator platform. The shift solenoid is part of the shift manifold.
Shift solenoid (3) controls the oil flow used to shift the propulsion motors. When the shift solenoid is not energized, the propulsion motors operate in the low-speed range. When the shift solenoid is energized, the propulsion motors operate in the high-speed range.
When the propulsion mode is set to high, the machine ECM generates a digital signal to energize shift solenoid (3).
The shift manifold contains three ports. The ports are labeled for identification. Charge oil is directed from port"PS" of the vibratory pump to port"P" of the shift manifold. Port"C" of the manifold is connected to the shift inlet passage of the axle motor and the drum motor. Port"T" of the shift manifold is connected to the hydraulic tank.
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| Illustration 4 | g06121891 |
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Under Front of Operator Platform (4) Test manifold (5) Pressure tap (in port "AF") (6) Pressure tap (in port "DF") (7) Pressure tap (in port "DR") (8) Pressure tap (in port "AR") | |
Test manifold (4) is located under the front of the operator platform. This manifold contains the balance lines for the propulsion circuit and also contains four pressure taps.
The forward circuits of the axle and drum propulsion systems are connected through an orifice in test manifold (4). The reverse circuits of the axle and drum propulsion systems are also connected by an orifice in this manifold. Each orifice restricts oil flow between the axle circuit and the drum circuit. The orifices prevent all flow from the drum circuit to flow to the axle circuit if the tires begin to spin. The orifices also prevent all flow from the axle circuit to flow to the drum circuit if the drum begins to spin.
The orifices allow oil to transfer between the drum and axle propulsion circuits. This oil transfer modulates the pressure difference in the hydrostatic drive circuits of the drum and axle propulsion systems. Oil transfer between the two systems is necessary to compensate for the following situations:
- Differences in underfoot conditions
- Differences in speeds between the drum and the wheels during turns
- Differences in rolling radii between the drum and the tires
The loop balance orifices aid in synchronizing the speeds of the drum and tires. Some oil is allowed to transfer between the loops when the speed of the drums and the wheels drifts out of synchronization. The orifices are sized to allow a limited transfer of oil, while allowing loop pressures to develop independently for automatic traction (anti-slip) control.
Pressure in the axle forward circuit can be measured at pressure tap (5) in port"AF" of test manifold (4). Pressure in the drum forward circuit can be measured at pressure tap (6) in port"DF" in the manifold. Drum reverse pressure can be measured at pressure tap (7) in port"DR" of the manifold. Axle reverse pressure can be measured at pressure tap (8) in port"AR" of the manifold.