TRACK LEVELLING AND TAMPING MACHINE WITH HYDRAULIC PRESSURE CONTROL SYSTEM

摘要

In a mobile track leveling and tamping machine, a hydraulic control system operates a drive for reciprocating vibratory tamping toots. The system includes a hydraulic fluid containing receptacle, a three-way proportional electro-hydraulic valve having an outlet connected to one cylinder chamber of the drive and another outlet connected to the hydraulic fluid containing receptacle, a hydraulic pressure regulator steplessly adjustable to a desired maximum tamping pressure exerted by reciprocation of the tools, a differential element having two inputs and an output connected to the valve, and a threshold value stage connected between the transmitter and one of the differential element inputs, the other input being connected to the regulator and a third outlet of the valve being connected to the other cylinder chamber whereby the hydraulic pressure therein is controlled in response to the threshold value.