Engine control unit
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Robomatic is the name of a diesel engine control unit which is claimed to prevent engine seizure, regardless of its cause, and is made by Stewart Automotive Equipment. Developed from the Mark 1 Robomatic, the Mark 2 unit ccimprises an electronic control box which incorporates early warning lights and a buzzer, an engine temperature sensor, which is mounted on the block of the engine, and a fuel solenoid valve, which is connected to the fuel injection pump with the aid of compression unions.
The oil pressure is monitored through the existing oil pressure switch, or alternatively (if a gauge is fitted) through a T union and switch.
The control box monitors both engine temperature and oil pressure, and in the event of a malfunction either system produces a combined audible and visual warning for a period of 25 sec. After 25 sec the current to the fuel valve is cut off, the valve closes and the engine comes to a halt.
Until such time as the fault is rectified the engine can be restarted only for maximum periods of 25 sec. Simultaneous with the valve closing, the buzzer stops and the warning light is pulsed, which prevents any damage to the Robomatic should the engine be stopped on the stop control and the vehicle electrics be left on inadvertently.
The control box measures 78mm x 75mm x 31mm and has three warning lights mounted in the front hooded section — amber for low oil pressure, red for excessive engine temperature and clear for a low oil or water level. It is installed in the cab with a shaped bracket which allows the box to swivel through an arc, thereby ensuring ease of fitment. Four wires run from the rear of the box to the oil switch, temperature sensor, solenoid valve and feed.
Precision-made for operation at 1 05deg C the temperature sensor is mounted on an aluminium plate which in turn is fitted under an engine block bolt. Having been switched to a preset temperature it remains in that position until the block temperature has dropped by 10deg C. On V engines the fitting of two sensors is recommended.
Based on the original diesel solenoid valve developed specifically for commercial vehicle operation in 1 959, the current diesel fuel solenoid is used in the Robomatic. It is a fail-safe design, is continuously rated and is adaptable to all diesel engines. One of the salient features of the valve is its ability to restart any engine — having stopped it on the valve — without having to vent the fuel system.
Made by: Stewart Automotive Equipment, Sherbourne Drive, Windsor, Berkshire SL4 4AE.