| 摘要 |
1,264,238. Change-speed control. CATERPILLAR TRACTOR CO. 11 Nov., 1969 [29 Nov., 1968], No. 55093/69. Heading F2D. A torque converter-retarder lock-up system for a dual power source i.e. front and rear engined vehicle such as a scraper having unmatched transmissions e.g. the front and rear transmissions may be eight and four speed units respectively, comprises a lock-up clutch 17 arranged across a torque converter 19 of a rear engine 11 and hydraulically operated to lock said converter 19 to give a direct mechanical drive between the engine 11 and its transmission (not shown) only and always when hydrodynamic braking via a retarder 21, 23 is required. Control is effected via a manually controlled modulating air valve 25 for pneumatic operation, via a duct 33, of a spool valve 38 which supplies hydraulic pressure via ducts 43, 49 to engage the lock-up clutch, a control valve 52 being simultaneously pneumatically operated via a duct 31 to modulatably actuate i.e. progressively charge the retarder 21, 23 with hydraulic fluid from the converter 19 via ducts 57, 59, the valve 52 additionally exhausting fluid from the retarder via a duct 61 and passing it through heat exchangers 65 and 63 via ducts 67, 69 and 71 before returning the fluid to the transmission lubricating system via a duct 64. Pneumatic pressure from the manual air valve 25 also passes via a duct 39 to a front retarder control (not shown) for modulatably actuating a front transmission retarder (not shown). |
