GB961226A - Monitoring system for power operated roof supports - Google Patents

Abstract

961,226. Hydraulic apparatus. ELECTRO-HYDRAULICS Ltd. June 19, 1962 [June 19, 1961], No. 22120/61. Heading F1P. Means for monitoring the support units of a power operated roof support system comprises means selectively to connect each roof support unit to indicating means, and switch means associated with each support unit to be operated dependent upon its condition and which in the event of a fault occurring in a support unit operate to halt the operation of the selecting means so that selection of the support units stop with the indicating means indicating the faulty unit. The means for monitoring the support units includes, in addition to the control system shown in Figs. 1 and 2 of Specification 961,225, a monitor position for the master switch 30, an additional circuit connecting in parallel switches S7, S8, PS1, PS2 which are normally open, an impulse unit 116 and relays A2, A3: switches PS1, PS2 close if the pressure in the props drops and switches S7, S8 close if the props extend to their full extent when they may not be supporting the roof. The relay A2 has rectifiers 107, 109 which permit its actuation only when the switch 30 is moved to the monitor position, and the relay Al which is actuated when the switch operated by the full extension of the advancing ram for the support unit is closed has rectifiers 110, 111 which permit the relay A1 to be actuated only when the switch is in the automatic or manual position. When the switch 30 is moved to the monitor position, a circuit is completed through the banks B1, B3 of the uniselectors US1, US2 to energize relay A2 closing a contact A2/2 in the circuit including the switches normally open contacts of switches S7, S8, PS1, PS2. A circuit is also completed through the impulse unit 16 which stops the wiper arms of uniselectors from one position to the next to sequentially energize the relays A2 associated with the support units and illuminate the associated lamps of the indicator 50. If a fault has occurred in one of the units, one of the switches S7, S8, PS1, PS2 associated with that unit closes to energize the relay A3, the contacts of which close a holding circuit for the relay and de-energize the impulse unit so that monitoring stops with the lamp of the faulty unit illuminated. Other switches may be included in the circuit to indicate faults in the advancing mechanism of the units. The Specification also includes a description of the monitoring system described with reference to Figs. 3A and 3B of Specification 961,225.