| 摘要 |
An empty/load changeover valve for a railway freight car having a proportioning valve via which the car control valve supplies and releases brake cylinder pressure. The proportioning valve comprises a balance piston having equal opposing pressure areas and a check valve integral therewith, one pressure area of the balance piston being subject to air supplied to the brake cylinder under all conditions of car loading. The opposing pressure area is of the balance piston either pressurized or depressurized depending upon the car load condition to accordingly establish a proportional mode of brake control only under empty conditions of vehicle loading. A release control valve is provided to assure release of the brake cylinder pressure in bypass of the proportioning valve check valve, and a lock-out feature prevents car rock and roll from affecting operation of the proportioning valve under empty conditions of car loading.
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