Patent GB-1132333-A (GB)
Title: Improvements in or relating to the bleeding of a hydraulic fluid system
Inventor: GREENWOOD THOMAS ERIC
IPC: B60T17/22
Filed: 1964-12-14
Abstract: 1,132,333. Hydraulic brakes. TECALEMIT (ENG.) Ltd. 3 Dec., 1965 [14 Dec., 1964], No. 50903/64. Headings F2E and F2F. [Also in Divisions B1 and F1] In an apparatus for use in bleeding an hydraulie fluid system, an auxiliary reservoir 1 is connected by a fluid outlet pipe 17 and an air return pipe 8 and a cap 12 for connecting these pipes to the hydraulic fluid system, the cap being provided with an air inlet so that hydraulic fluid can flow through inner pipe 17 from the auxiliary reservoir to the system while air is admitted to the auxiliary reservoir through a space between the pipes so long as the end of the air return pipe 8 is not covered by hydraulic fluid in the system; and a drainage reservoir 20 is adapted to receive fluid bled from the system and includes at least one inlet connection (22) connecting the reservoir to a bleed outlet of the system, a non-return valve 36 to prevent flow of fluid from the drainage reservoir back through the inlet into the system, an outlet 28 for the discharge of hydraulic fluid which has been collected in the drainage reservoir. When applied to a braking system for bleeding air therefrom, the auxiliary reservoir 1 shown in Fig. 1 is formed of translucent plastics material and is connected with the reservoir of the hydraulic braking system by means of coaxial connecting pipes 17, 8 and an adaptor cap 12 which replaces the existing cap on the reservoir of the hydraulic brake system. If the level of the hydraulic fluid in the reservoir of the hydraulic brake system is below the end 14 of the pipe 8, air enters va a vent 18 and passes through the annular space between the pipe 8 and the internal tube 17 to enter the auxiliary reservoir 1. The brake fluid then enters the reservoir 45 from the bottle 1 through the tube 17 until the lower end 14 of the pipe 8 is covered. This level of brake fluid in the system will be maintained until the bottle 1 is empty. The drainage reservoir 20 is in the form of a bottle of translucent plastics material and is adapted to receive fluid ejected through the bleed pipes 39 and 26 connected to bleed screws on the vehicle braking system and when the vehicle brake pedal is depressed the brake fluid will be ejected through the pipes 39 and 26 into the bottle 20. Any air expelled from the vehicle hydraulic brake system will be visible as the hydraulic fluid passes through the transparent pipes 26 and pumping is continued until a clear flow is seen. Since the fluid enters the drainage bottle 20 through non-return valves 36 it cannot be drawn back into the hydraulic brake system when the brake pedal is released. The drainage bottle 20 may then be emptied into a suitable container through its outlet pipe 28 by inverting the bottle and squeezing it. The non-return valves 36 again prevent fluid from passing back through the extension tubes 33 and fluid passes through a filter 29 and the pipe 28 into the drainage container. Each non-return valve 36 is formed of an elastomeric material and is of generally tubular form having one end which is fitted on to the tube 33 and the other end which is normally closed but is formed with at least one slit 37a through which fluid bled from the system is discharged into the reservoir 20.