Improvements in the manufacture of pre-stressed reinforced concrete members such as railway sleepers and beams

摘要

666,712. Automatic temperature control systems. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. Feb. 13, 1950 [Feb. 14, 1949], No. 3998/49. Class 38 (iv). [Also in Group V] Prestressed reinforced concrete is heated by electricity passing through the reinforcing wires C, C1. The electrical supply is reduced or interrupted when the concrete temperature exceeds a predetermined maximum, and is increased or reconnected when the temperature falls below a predetermined minimum. This variation of electrical supply is effected through a thermostat D and a cut-out relay L and a circuit breaker OCB. Specification 641,827, [Group V], is referred to.