GB1471305A - Vehicle systems monitor - Google Patents

Abstract

1471305 Indicating working conditions CATERPILLAR TRACTOR CO 10 May 1974 [14 May 1973] 20865/74 Heading F1B A monitor system for signalling the existence of any of a'plurality of undesirable operating conditions in a motorized vehicle comprises at least one first sensor which, in response to an undesirable operating condition of a kind which does not require immediate correction, actuates a first switch and first circuit means which actuate a first indicator device having means for signalling to an operator, latching means for holding the first indicator device in an actuated condition even after the vehicle is shut down and means for resetting the latching means; and including a second sensor which in response to a condition which requires immediate correction, actuates a second switch and second circuit means which actuate a second indicator device having distinguishably different means for signalling an operator and which terminate actuation of the second indicator device in response to deactuation of the second sensor switch. An earth-moving vehicle has an engine coolant temperature sensor 11 which closes normally open switch 11' when the engine overheats, oil pressure sensor 12 which closes normally open switch 12' when oil pressure is too low, air filter flow sensor 13 which opens normally closed switch 13' when flow through the air filter is reduced by blockage, a hydraulic fluid level sensor 14 which closes normally open switch 14' when the fluid level is low, a hydraulic fluid filter flow sensor 16 which opens normally closed switch 16' when the filter is blocked and hydraulic fluid temperature sensor 17 which opens normally closed switch 17' when the fluid overheats. Air filter flow switch 13', when opened starts timer 42 and if the switch is still open after 15 seconds, lamp 29 is illuminated and remains on, even after the vehicle is shut down. The lamp is extinguished only when switch 23 is opened. Hydraulic fluid filter warning lamp 32 is controlled in a similar way by switched 16' and timer 61. Switch 17' opens only when the hydraulic fluid temperature has reached normal level and its viscosity has fallen. Hydraulic fluid level warning lamp 34 is illuminated when switch 14' closes and remains closed for more than two seconds, timer 76 being set to measure this period. To indicate that this is an emergency condition requiring immediate correction, a lamp 37 flashes at the same time, under the control of astable multi-vibrator 92. Lamp 37 also flashes when either or both of switches 11', coolant temperature, or 12', low oil pressure, are closed. Dial indicators 18 enable the particular cause to be identified. To test the operation of the warning circuits, lead 123 is connected to the glow plugs heater supply terminal so that the lamps are energized while the engine control switch 114 is in the pre-heat or start positions.