| 摘要 |
974,482. Electric selective signalling. CATERPILLAR TRACTOR CO. May 13,1963 [June 15,1962],No. 18812/63. Heading G4H. [Also in Division G3] In a remote control system for master and slave transmissions of a vehicle e.g. an earth moving machine, a cam 51 in the slave transmission control maintains all but an adjacent pair 54d, e of a plurality of series-connected switches 54a.. 54f closed, a master control 26 places an electrical signal on one of a plurality of conductors 86a.. 86e each of which is connected to a series connection between a pair of the switches 54a.. 54f, and an electrically-actuated servo 62 is arranged to move the cam 51 in one direction or the other if it receives a signal from the first or the last respectively of the series of switches 54a.. 54f. In Fig. 3A, master control 26 comprises a cam 31 which is set in one of five angular positions when the vehicle driver sets the master transmission gear ratio (three forward and one reverse ratio and neutral are possible). Cam 31 thus closes one of five switches 34a.. 34e to energize one of lines 86a.. 86e. If the position of cam 51 does not correspond to that of cam 31, the potential on the selected line 86a. . 86e is communicated to one of two lines 88, 91 thus actuating one of two solenoidoperated valves 106, 107 of a hydraulic servo 62 to bring cam 51 into correspondence and change the gear ratio of the slave transmission to that of the master transmission. The master and slave transmissions may be associated with main and auxiliary engines in a tractor and a scraper connected to it respectively. A pressure switch 82 is provided to cut off the power supply if the main engine stops unexpectedly, thus preventing the slave control overriding the master control. A switch 83 enables the slave gearing to be put into neutral whatever the state of the master gearing. Fig. 4 (not shown) shows a fail-safe modification in which an extra set of switches and an extra cam both identical to those of the master control 26 are provided in the slave control 27 to energize a signal line if the master and slave transmissions are in the same state. If the slave control 27 ceases to follow the master control 26, this line is de-energized thus extinguishing a lamp and deenergizing a solenoid-operated hydraulic valve to pass fluid to set the slave transmission in low gear. A fluid-actuated switch is also provided which sets the slave in low gear whenever the master is so set. In other applications, the servo 62 could be electrical or pneumatic. Specification 974,481 is referred to. |
