Improved safety circuit for hydraulically driven transfer pump - for used oil etc. in road tanker

摘要

Safety circuit for a hydraulically-driven transfer pump in a road tanker. In the hydraulic pressure-line (6) and return-line (8) of the pump's hydraulic motor (12) there is a pneumatically-controlled multi-way valve (7) whose control-air connection pipes (35,36) are connected to a manual lever switch (25). This has a control-air connection (21) connected to the outlet (30) of a pneumatic storage module (4) having multi-way valves (17,18) and change-over valves (16,29). Several further features and variants are claimed, including connection of the pressure switches (2,3) to the leakage-oil pipe (23) leading into the hydraulic system tank (34) from the hydraulic motor (12). USE/ADVANTAGE - The road tankers concerned have a hydraulically-driven pump used for both filling and emptying. Such tankers are used, e.g., for carrying used oil. This is an improved safety circuit in which (unlike in some earlier systems) the safety function is not adversely affected when the pump is used after the hydraulic system has been switched off.