FR2500897A1 - Hydraulic brake operating cylinder - has screwed spindle with double-acting notched adjusting nut for taking up play - Google Patents

Abstract

The brake cylinder consists of a body (1) with a hydraulically operated piston (2) and a return spring (3). The adjusting spindle (4) screws into an outer tube (5) which also contains a spring (6) acting between the base of the tube and the piston. The spindle head (7) is in the form of a notched adjuster with a chamfer on either side. The head engages, with clearance, with an annular, internal groove in the piston. The head (7) of the spindle rests against a spring loaded thrust bearing (12). An extension (4A) to the spindle engages in the bore of a spacer (15).

Description

 The present invention relates to improvements made to brake adjusters.

 In the family of brake adjusters, there are single and double action devices.

 Single action devices automatically reduce excessive play in a brake linkage.

This excessive play (j) can occur during wear of the braking surfaces for example.

Double action devices, in addition to the previous operation, automatically compensate for too little play (j) by increasing it. This too weak play can occur for various reasons (replacement of brake shoes, sagging of suspension etc ...)
We know in particular a brake adjuster which is double or single action depending on whether one is mounting or not mounting a spring, a ball bearing and a cup, relative to the general structure of the adjuster.

 The present invention relates to an arrangement making it possible to make the single-action adjuster in the released brake position while maintaining its operating characteristics of instantaneous single or double action slack adjuster when tightening and loosening.

 In addition, it strengthens the locking of the device in the released brake position.

Other characteristics and advantages of the present invention will emerge from the description which follows, given with reference to the appended drawing, in which
- Figure 1 is a side elevational view and half section of a brake adjuster equipped according to the invention;
- Figure 2 is a sectional view, on a larger scale, of a part of this adjuster.

 In the embodiment shown, the brake adjuster equipped according to the invention comprises, in the known manner, in a cylinder body (1) a piston (2) with return spring (3) between the body and the piston. An adjustment rod (4) is also provided in the cylinder body with a tube (5) screwed onto said rod. A spring (6) is placed between the bottom of the tubing (5) and the piston (2). The adjustment rod (4) comprises a nut (7) with two possible conical couplings (8-9) and (10-11) with the piston (2).

 Of course, the brake adjuster can also include the ball stop (12) the spring (13) and the cup (14) which was discussed above. The spring (13) is placed between the ball bearing (12) and the piston (2) by means of the cup (14). The nut (7) integral with the adjustment rod 4 is supported on the ball stop (12).

 According to the invention, the thrust ball bearing (12) rests on a shim (15) itself bearing on the cylinder body (1). The wedge is cylindrical and covers the extension (4A) of the rod 4. A compression force applied between the tubing (5) screwed on the rod (4) and the body (1), does not act on the conical coupling notched (8-9) which remains in engagement. The adjustment rod (4) is thus locked in translation. It cannot therefore rotate and cause the device to shorten. Reversibility is thus eliminated.

 The invention also provides a clearance B between the piston (2) and the cylinder body (1) and this clearance determines the reinforcement of the locking. Indeed, the return spring (3) resting in the body (1) presses the piston (2) against the nut (7) by the notched conical coupling (8-9). This force is transmitted to the body (1) by the parts (12) and (15) as described above. The force of the return spring (3) is therefore added to that of the spring (6) and possibly that of the spring (13) which load the notched conical coupling (8-9).

 During tightening and loosening, the shim (15) retracts in translation in the piston (2) by reducing a clearance (C) existing between an annular rib 16 of the shim (15) and the piston (2) of so as to allow the notched conical coupling (10-11). We then find the operating characteristics of the double or single instantaneous action slack adjuster depending on whether the spring (13), the ball stop (12) and the cup (14) are mounted or not mounted. .

 In general, the invention applies to brake assemblies with brake adjusters and finds particular application, but not exclusively, on maneuvering machines.

 It is understood that the present invention has only been described and shown as a preferred example and that it is possible to provide equivalences in its constituent elements without, however, departing from the scope of the invention.

Claims (3)

 1. Piston brake adjuster in a cylinder body, comprising an adjustment rod, a tube screwed onto said rod and a spring placed between the bottom of said tube and said piston, said rod comprising a nut with two possible conical couplings with said piston, which brake adjuster can be equipped, depending on the desired operation, between said nut and said piston, with a ball stop of a cup and a spring, characterized in that it further comprises, means (15) for locking in translation of said adjustment rod (4) so that the adjuster can be made to single action in the released brake position while maintaining its operating characteristics of instantaneous single or double action slack adjuster at tightening and loosening.  2. Brake adjuster according to claim 1, characterized in that a clearance (B) is provided between the piston (2) and the cylinder body (1) which determines the reinforcement of the locking in the released brake position.  3. Brake adjuster according to any one of claims 1 and 2, characterized in that the locking means (15) is a cylindrical shim capable of coming to bear on the cylinder body (1).