GB793229A - Improvements in tensioning means for endless conveyors - Google Patents

Abstract

793,229. Endless conveyers. STAHLWERKE BRUNINGHAUS GES. Dec. 18, 1956 [Jan. 19, 1956], No. 38581/56. Class 78 (1). An endless belt or chain conveyer includes hydraulically acting tensioning means provided with an hydraulic pressure-sensitive device adapted to switch off the drive of the conveyers and if necessary associated components, when a permissible tractive force in the belt or chain is exceeded. As shown, a conveyer belt 17 passes over a driving drum driven by a motor 10 and a tensioning drum carried by slidable bearings secured to the piston rods of a pair of cylinders 4 in which hydraulic fluid is adapted to be maintained at a predetermined pressure. In the form shown in Fig. 1 this is accomplished by a pressure-sensitive switch 6 controlling the motor 7 of a pump 1 for the hydraulic fluid. A non-return valve 3 prevents fluid returning from cylinders 4 and provides means whereby an increase in tractive force in the belt causes a rise in the pressure of hydraulic fluid which when excessive actuates a spring-controlled piston 8 acting on a switch 9 to cut off motor 10. In an alternative form, Fig. 3, the motor 7 is driven continuously to circulate hydraulic fluid through a pressure relief valve 11 and instead of a spring-loaded piston, a double piston 14, 16 is provided which is moved to actuate the switch 9 when the pressure in cylinders 4 exceeds the setting of an adjustable pressure relief valve 12. This movement of the pistons 14, 16 connects to the cylinders 4 to a conduit 15 relieving them of pressure, and actuates switch 9 to switch off both of the motors 7, 10.