| 摘要 |
An empty/load changeover valve device for a railway car having a proportioning valve including a valve member via which brake cylinder pressure is supplied and released and a balance piston to which the valve member is connected. The balance piston has equal opposing pressure areas both of which are subject to brake pressure in the "load" setting of the changeover valve device, one of the pressure areas being vented in the "empty" setting, thereby establishing either a non-proportioning mode of brake control or a proportioning mode of brake control. In the "empty" setting, brake supply pressure is connected to an equalizing reservoir. A regulating valve is provided to interrupt this connection until the brake supply pressure reaches a predetermined value, thereby preventing the other pressure area of the balance piston from being unloaded sufficiently to cause an inadvertent opening of the check valve member and a consequent drop in brake cylinder pressure.
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