Automatic brake speed bleed system

In a brake system (10) having a hydraulic brake (12,13) provided with spring means (26) for applying the brake and fluid pressure responsive means (24) for overcoming the spring means (26) for releasing the brake (12,13), said pressure responsive means defining a pressure chamber (23) having a lower portion (22) and an upper portion (34), a supply line (14) to said lower portion (22), and a control (16) for selectively directing pressurized hydraulic liquid from a sump (21) through said supply line (14) to release the brake (12,13), means for effecting concurrent self-bleeding of the brake and self-flushing of debris from the brake, comprising:

• a bleed outlet (33) opening to said upper portion (34) of the brake pressure chamber (23) and connected in series with said supply line (14), said outlet (33) having a check valve (36) permitting flow only outwardly from said upper portion (34) of the brake pressure chamber (23), hydraulic liquid passing into said pressure chamber (23) only through said supply line (14), hydraulic liquid only being passed outwardly through said supply line (14) and hydraulic liquid and air which being permitted to collect in said upper portion (34) of the brake pressure chamber (23) are passed outwardly through said bleed outlet (33) by the action of said spring means (26) when the hydraulic fluid pressure applied to the brake pressure chamber (23) is relieved;
• and
• means for connecting said bleed outlet (33) and supply line (14) to receive the hydraulic liquid from both the upper and lower portions of the pressure chamber (23) when the hydraulic fluid pressure is so relieved for subsequent return to the sump (21).

In a vehicle provided with a speed and direction control lever (17) selectively positionable in forwardly, reverse, and neutral positions, and a brake system (10) having a hydraulic brake (12,13) provided with spring means (26) for applying the brake and fluid pressure responsive means (24) for overcoming the spring means (26) for releasing the brake (12,13), said pressure responsive means (24) in part defining a pressure chamber (23) having a lower portion (22) and an upper portion (34), a hydraulic liquid supply line (14) to said lower portion (22), and means (16) associated with said control lever (17) for selectively directing pressured hydraulic liquid from a sump (21) through said supply line (14) to release the brake (12,13) whenever the control lever (17) is in forward or reverse positions, means for effecting self bleeding of the brake (12,13) comprising:

• a bleed outlet (33) opening to said upper portion (24) of the brake pressure chamber (23) and connected in series with said supply line (14), and having a check valve (36) permitting flow only outwardly from said upper portion (34) of the brake pressure chamber (23), hydraulic liquid passing into said pressure chamber (23) only through said supply line (14), hydraulic liquid only is passed outwardly through said supply line (14) and hydraulic liquid and air which may collect in said upper portion (34) of the brake pressure chamber (23) are passed outwardly through said bleed outlet (33) by the action of said spring means (26) as an incident of the control lever (17) being positioned in the neutral position to relieve the hydraulic fluid pressure applied to the brake pressure chamber (23);
• and
• means for connecting said bleed outlet (33) and supply line (14) to receive the hydraulic liquid from both the upper and lower portions of the pressure chamber (23) when the hydraulic fluid pressure is so relieved for subsequent return to the sump (21).