General Information

SMCS Code: 7600-ZM

This module details the standard, PROPORTIONAL type, remote control system as fitted to Elphinstone R2900 L.H.D. machines. There may be some variation between this standard configuration and a customer driven modification to the remote control system. For further information on modified or other types of systems, contact your local Caterpillar dealer.

NOTE: The remote control system controls components which are also part of the machine electrical, hydraulic, steering, braking and power train systems. This module contains information on the remote control components and interface connected to these machine systems.

Reference: For further information on the machine systems, refer to the relevant machine systems section of the machine Service Manual.

Remote Control System Schematic
(1) Steering and bucket control valve group. (2) Solenoid operated directional control valve. (3) Solenoid control valves. (4) Transmitter. (5) Interface logic box. (6) Receiver.

Location of the Remote Control System Components
(1) Steering and bucket control valve group. (2) Solenoid operated directional control valve. (3) Solenoid control valves. (5) Interface logic box. (6) Receiver.

The remote control system is made up of the following components; transmitter (4), interface logic box (5), receiver (6) and the machine electrical and hydraulic interface components.

The machine interface includes steering and bucket control valve group (1), solenoid operated directional control valve (2) and solenoid control valves (3) and various components of the machine electrical, steering and hydraulic systems.

Remote Control Transmitter (Typical Example)
(4) Transmitter.

Transmitter (4) is used by the operator to control machine functions by remote control. The transmitter sends radio frequency signals to the receiver.

The transmitter is powered by a separate power source. All other components in the remote control circuit are powered by the machine electrical system.

Location of the Receiver
(6) Receiver.

Receiver (6) for the remote control system is located in the machine hydraulic tank compartment.

Receiver (6) interprets the radio signals from the transmitter. The receiver sends an output for each remote control function to the interface logic box.

Location of the Interface Logic Box
(5) Interface logic box.

Interface logic box (5) for the remote control system is located in the transmission compartment.

Interface logic box (5) contains a relay for each remote control function. The receiver output will activate the corresponding logic box relay. The relay will switch power to the machine hydraulic interface.

The interface logic box has two types of outputs; electrical outputs and solenoid outputs. The electrical outputs are connected directly to the machine electrical system. The solenoid outputs are connected to the machine steering and hydraulic systems through steering and bucket control valve group (1).

Location of the Steering and Bucket Control Valve Group
(1) Steering and bucket control valve group. (2) Solenoid operated directional control valve. (3) Solenoid control valves.

Steering and bucket control valve group (1) is located beside the operator's station door in the articulation hitch area of the machine.

The steering and bucket control valve group contains four solenoid control valves (3) and a solenoid operated directional control valve (2). The solenoid control valves control the machine bucket functions and the directional control valve controls the machine steering functions.

Transmitter

SMCS Code: 7600-ZM

Remote Control Transmitter (Typical Example)

The remote control transmitter allows the operator to operate the machine by remote control. The transmitter output is to the remote control receiver.

When a function is selected on the transmitter, a radio signal is sent to the receiver on the machine. The receiver and the machine interface cause a machine function to occur. The transmitter can start, stop and control almost all the functions of the machine.

The transmitter has several safety features. The transmitter must be turned on and in radio range of the receiver. If it is not, the parking brake will engage and the machine engine will shut down.

The transmitter has a 'deadman' function. On 'proportional' type remote control systems, the brakes are applied whenever the directional control joystick is in the center position. The joystick returns to the center position whenever it is released. Some transmitters have a 'deadman' switch that must be activated to allow the brakes to release and remote control functions to be selected.

Some types of transmitters also contain a tilt switch which will cause the transmitter to turn off if it is tilted beyond 45°. This will cause the machine parking brake to engage and the engine to shut down.

Reference: For basic machine operational details for the Control Master transmitter, refer to the Operation and Maintenance Manual for the machine that is being serviced.

Reference: Other brands of transmitter and receiver may be used with the Elphinstone remote control interface. For operational details on the transmitter and receiver for your machine, refer to the manufacturer's instructions or contact the supplier of the transmitter and receiver.

Receiver

SMCS Code: 7600-ZM

Remote Control Receiver

The remote control receiver has an input and an output. The input is from the transmitter radio signals. The output is to the interface logic box.

When a function is selected on the transmitter, a radio signal is sent to the receiver on the machine. The receiver interprets the signal from the remote control transmitter. The receiver then sends an electrical signal to the remote control interface logic box. The interface logic box causes a machine function to occur.

Interface Logic Box

SMCS Code: 7600-ZM

Interface Logic Box

The remote control interface logic box has an input and an output. The input is from the receiver. The output is to the remote control interface and the machine electrical system.

The function of the logic box is to provide a connection or interface between the remote control system and the machine. It also minimizes the current draw through the remote control receiver. This results in improved receiver life.

Interface Logic Box
(1) Receiver input connector. (2) Circuit breaker (10 amp). (3) Machine interface output connector. (4) Relay for proportional functions. (5) Relay for ON/OFF functions. (6) Circuit breaker (10 amp). (7) Electrical interface connector.

The interface logic box contains an input connector (1) from the receiver, two circuit breakers (2) and (6), twenty-one relays (4) and (5), an output connector (3) to the machine interface, and an interface connector (7) to the machine electrical system.

Two 10 amp automatic reset circuit breakers (2) and (6) are mounted in the center of the interface logic box. The circuit breakers protect the electrical circuits of the remote control receiver, the logic box and the machine interface.

The interface logic box contains twenty-one relays and bases for each remote control function. There are two types of relays used in the interface logic box: seven relays (4) for proportional functions (Hella relays), and fourteen relays (5) for direct or ON/OFF functions (Bosch relays).

When the receiver sends an electrical signal for an ON/OFF function, the relay for that function will be activated. The relay switches power to the relevant solenoid or circuit.

When the receiver sends an electrical signal for a proportional function, the relay for that function passes this electrical signal through to the relevant solenoid.

Interface Logic Box Relay Layout

Interface Logic Box (R2900-101 to 165)
(1) Receiver input connector. (2) Circuit breaker (10 amp). (3) Machine interface output connector. (4) Relay for proportional functions. (5) Relay for ON/OFF functions. (6) Circuit breaker (10 amp). (7) Electrical interface connector.

Interface Logic Box (R2900-166 to 170, 5TW1-Up)
(1) Receiver input connector. (2) Circuit breaker (10 amp). (3) Machine interface output connector. (4) Relay for proportional functions. (5) Relay for ON/OFF functions. (6) Circuit breaker (10 amp). (7) Electrical interface connector.

NOTE: The shaded relays (4) in the above illustrations are used for proportional remote control functions.

Relay #17 is the engine stop relay. If the transmitter is turned off when the dash remote control switch is turned to the ON position, relay #17 will not be energized causing the engine to shut down.

If the transmitter is turned on, relay #17 will energize when the dash switch is turned on and the engine will not shut down.

If a fault occurs and the transmitter or receiver loses power, relay #17 will no longer be energized causing the engine to shut down.

Interface Logic Box Electrical Schematic

Interface Logic Box Electrical Schematic (R2900-101 to 165)
(1) Receiver input connector. (2) Circuit breaker (10 amp). (3) Machine interface output connector. (4) Relay for proportional functions. (5) Relay for ON/OFF functions. (6) Circuit breaker (10 amp). (7) Electrical interface connector.

Interface Logic Box Electrical Schematic (R2900-166 to 170, 5TW1-Up)
(1) Receiver input connector. (2) Circuit breaker (10 amp). (3) Machine interface output connector. (4) Relay for proportional functions. (5) Relay for ON/OFF functions. (6) Circuit breaker (10 amp). (7) Electrical interface connector.

Reference: For more information on the machine electrical system, refer to the Electrical Schematic for the machine that is being serviced.

Remote Control Interface

SMCS Code: 7600-ZM

The remote control interface is used to make the machine perform certain functions. The interface has an input and an output. The input is from the remote control interface logic box. The output is to the machine electrical system, the implement hydraulic system, the steering system and the braking system.

The remote control interface consists of switches, wiring and solenoid control valves.

Remote Control Interface Electrical Components

Operator's Compartment
(1) Remote control circuit breaker.

Remote control circuit breaker (1) protects all remote control electrical circuits. The circuit breaker will 'trip' if there is an overloaded circuit. The circuit breaker can be reset by pushing the button in. If the button does not stay in, or comes out shortly after being reset, the remote control electrical circuit must be checked.

Operator's Compartment
(2) Remote control switch.

Remote control switch (2) is used to supply power to the remote control receiver and the interface logic box. If this switch is turned on while manually operating the machine, the engine will shut down and the parking brake will automatically engage.

Machine Hood
(3) Remote control parking brake indicator light (amber).

Remote control parking brake indicator light (3) is mounted on the engine hood of the machine.

Amber parking brake indicator light (3) will be illuminated when the parking brake is applied while operating the machine on remote control. When the parking brake is released by the transmitter, the light should go out.

Remote Control Interface Hydraulic Components

Remote Control Hydraulic Interface Components
(1) Steering and bucket control valve group. (2) Solenoid operated directional control valve. (3) Solenoid control valves.

The machine interface hydraulic system controls certain machine functions. The system controls bucket lift, lower, dump and tilt back functions and right and left steering functions.

Steering and bucket control valve group (1) consists of four cartridge-type solenoid control valves (3) that control the bucket functions, and a solenoid operated directional control valve (2) that controls the steering functions.

The solenoid control valves and the directional control valve are connected to the machine hydraulic and steering systems through ports in the manifold assembly of the steering and bucket control valve group.

Reference: For more information on the steering and bucket control valve group, refer to Systems Operation, Testing and Adjusting, "Steering and Bucket Control Valve Group" for the machine that is being serviced.

Steering and Bucket Control Valve Group

SMCS Code: 5051-RCT

Steering and Bucket Control Valve Group Hydraulic Schematic
(1) Oil lines from steering pilot control valve (STIC steer) or steering metering pump (wheel steer) (for manual machine operation). (2) Oil lines from hydraulic pilot control valve (for manual machine operation). (3) Manifold. (4) Shuttle valve. (5) Tank return port. (6) Solenoid operated directional control valve. (7) Bucket lower solenoid control valve. (8) Bucket lift solenoid control valve. (9) Bucket dump solenoid control valve. (10) Bucket tilt back solenoid control valve. (11) Pilot oil supply port.

The remote control operation of the machine steering and bucket functions is controlled by the steering and bucket control valve group.

The steering and bucket control valve group contains a solenoid operated directional control valve (6) and four solenoid control valves (7), (8), (9) and (10) mounted in manifold (3). The solenoid operated directional control valve controls the machine steering functions and the solenoid control valves control the machine bucket functions.

The solenoid operated directional control valve and the solenoid control valves share a common supply of pilot pressure oil from the selector and pressure control valve in the machine hydraulic system.

A double-check or shuttle valve (4) for each bucket function is also located in the manifold of the steering and bucket control valve group.

Pilot oil lines (1) from the steering pilot control valve (STIC steer) or the steering metering pump (wheel steer) are connected to manifold (3).

Steering and Bucket Control Valve Group
(1) Oil lines from steering pilot control valve (STIC steer) or steering metering pump (wheel steer) (for manual machine operation). (2) Oil lines from hydraulic pilot control valve (for manual machine operation). (3) Manifold. (5) Tank return port. (6) Solenoid operated directional control valve. (7) Bucket lower solenoid control valve. (8) Bucket lift solenoid control valve. (9) Bucket dump solenoid control valve. (10) Bucket tilt back solenoid control valve. (11) Pilot oil supply port.

When the steering control is used to steer the machine for manual machine operation, steering pilot oil is directed to manifold (3) through one of the steering pilot oil lines (1). The directional control valve spool in the steering and bucket control valve group is in a centered position, blocking oil passages to and from the remote control system. This causes the steering pilot oil to be directed to the steering neutralizers and the steering control valve to steer the machine.

When the steering control lever on the transmitter is moved to the STEER RIGHT position, the receiver sends power via the interface logic box to energize the left solenoid on directional control valve (6). The solenoid moves the valve spool of the directional control valve. Pilot pressure oil from supply port (11) is directed to the spool in the steering control valve. Oil from the opposite end of the steering control valve spool is opened to the hydraulic tank through the directional control valve and return port (5). This allows the spool in the steering control valve to move and the machine steers to the right.

When the solenoid on directional control valve (6) is de-energized, the spool in the directional control valve is returned to the centered position by spring force. Pilot oil flow to and from the steering control valve is blocked by the spool. Trapped oil in the pilot end of the steering control valve is pushed through metering orifices in the valve by the force of the spool centering spring. The spool in the steering control valve is moved to the HOLD position and the machine stops articulating.

When the steering control lever on the transmitter is moved to the STEER LEFT position, the right solenoid on directional control valve (6) is energized. Pilot pressure oil is directed to the steering control valve to steer the machine to the left.

Pilot oil lines (2) from the hydraulic pilot control valve (joystick) are connected to manifold (3). When the pilot control valve is used for a bucket function, pilot pressure oil is directed to manifold (3). The shuttle valve for that function directs the pilot pressure oil to the main control valve in the front frame.

When the bucket control lever on the transmitter is moved to the RAISE position, the receiver sends power via the interface logic box to energize lift solenoid control valve (8). The valve directs pilot pressure oil from supply port (11) to shuttle valve (4) in manifold (3).

The shuttle valve blocks oil from going to the pilot control valve and directs oil to the main control valve. The pilot oil moves the control valve lift spool to the RAISE position to raise the bucket.

When the bucket control lever on the transmitter is released, it will return to the HOLD position. Solenoid control valve (8) will de-energize, allowing the pilot oil from the main control valve to return to tank through shuttle valve (4) and return port (5). The spool in the main control valve is moved to the HOLD position by spring force and the bucket remains stationary.

The operation of the other bucket functions is the same as the RAISE function.

Reference: For more information on the operation of the hydraulic system, refer to Hydraulic System, Systems Operation, Testing and Adjusting for the machine that is being serviced.

Reference: For more information on the operation of the steering system, refer to Steering System, Systems Operation, Testing and Adjusting for the machine that is being serviced.

Engine Throttle Control

SMCS Code: 1269-RCT

Electronic Engine Throttle Control
(1) Engine throttle control unit.

The operation of the engine throttle on remote control is controlled by the throttle control unit.

The throttle control unit has an input and an output. The input is from the remote control receiver via the logic box. The output is to the engine Electronic Control Module (ECM).

When the machine is operated on remote control, a radio signal for throttle control is sent from the transmitter to the receiver. The receiver changes this signal to a Pulse Width Modulated (PWM) signal. The PWM signal is sent to the interface logic box and then to throttle control unit (1). A resistor, inside the throttle control unit, reduces the low state voltage of the signal and sends a signal to the engine ECM to change engine speed to the desired rpm.