This invention relates to hydraulic annular piston brakes with hydraulically
operated self adjustment and return mechanism for earth moving machines
and tractors. This system is particularly useful for multidisc brakes where the
higher volume is required to compensate wear.
BACKGROUND1 PRIOR ART
1 Return mechanism pulls back the piston to it's originallno pressure positions,
after the removal of pressure applied through foot pedallbraking device to
avoid drag & power loss. Self-adjusting mechanism acts during extra travel for
friction disc wear and shift piston to the zero position, which maintains the net
travel. It facilitates the smaller size master cylinder and overcomes the
necessity of shims in assembly. Most of the current earth moving machines
and tractors are without self-adjusting or piston return mechanism due to
complexity and high cost against conventional system.
In some system a mechanically loaded & operated system is used. However, it
is inaccurate & can develop problem with fatigue. These system also require
pre setting & are difficult to assemble.
The conventional brake piston return mechanism used in earth moving
machines or tractors is shown in fig. 1 indicating plate spring (I), piston (2),
brake pad (3) and friction disc (4). It includes plate spring (1) to return the
piston (2) without any self adjusting mechanism. In this system, spring pulls
back the piston to zero position while pedal travel increases volume of brake
fluid, required for higher travel due with wear of brake discs.
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DRAWBACKS OF THE SYSTEM ARE AS FOLLOWS:-
! 1. It is difficult to assemble the system.
2. It requires shims to maintain the initial volume/ pedal position.
I 3. Requirement of large size master cylinder/braking device as the volume
displaced continuously increases with wear.
OBJECTS OF THE INVENTION
! The primary object of the present invention is to provide hydraulic annular
piston brakes with hydraulically operated self adjustment and return
mechanism for earth moving machines and tractors which overcomes
disadvantages associated with the prior art.
Another object of the present invention is to provide hydraulic annular piston
brakes with hydraulically operated self adjustment and return mechanism for
earth moving machines and tractors which is accurate and compact.
Further object of the present invention is to provide hydraulic annular piston
brakes with hydraulically operated self adjustment and return mechanism for
earth moving machines and tractors which is easy to assemble with cost
effectiveness in improving brake life and effectiveness.
Yet another object of the present invention is to provide hydraulic annular
piston brakes with hydraulically operated self adjustment and return
mechanism for earth moving machines and tractors which is efficient.
Yet another object of the present invention is to provide hydraulic annular
piston brakes with hydraulically operated self adjustment and return
mechanism for earth moving machines and tractors which is hydraulically
operated.
SUMMARY OF THE INVENTION
According to this invention, there is provided an arrangement of self adjusting
hydraulic brakes with piston return mechanism comprising of assembly of
washer, bolt, screw, check valve, compensating piston, sealing O-ring and
brake piston connected with a central housing.
I BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from
the ensuing description when read in conjunction with the accompanying
drawings and wherein:
Fig. 1 shows: conventional arrangement for piston return.
Fig. 2 shows: an arrangement of self adjusting hydraulic brakes with piston
return mechanism for earth moving machines or tractors according to the
present invention.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS
I This invention comprises an arrangement of self adjusting hydraulic brakes
with piston return mechanism.
When hydraulic pressure is applied, piston surface contacts with brake disc to
apply brake. After removal of foot pedal force, the piston goes back to no
pressure position to provide designated clearance between friction disc 8s
piston so as to avoid drag. Drag is continuous undesirable application of
brakes, leading to loss of power & high temperature. To avoid drag, the present
invention has been introduced.
ORIGINAL
Now, reference may be made to fig. 2. The present invention comprises
assembly of washer (4), bolt (51, screw (3); check valve [(Ball (2) & spring(l)],
Compensating piston (7), sealing O-ring (8) & Brake Piston (6). For this
assembly, all parts are fitted as per sequence; with central housing. The wear
compensator requires two units, placed diametrically opposite, on a suitable
PCD. The position of bolt w.r.t. piston is locked by lock washer & screw. Spring
& ball works as direction control valve which allows the brake fluid to flow in
one direction only from brake piston to cavity of compensating piston. Further,
the Set gap (A), is maintained during assembly.
Condition 1, with new friction disc: (self adjustment at no disc wear).
During braking, the annular piston moves out by pressure. The bolt pulls the
compensating piston fitted with external O-ring. During brake release, the
annular piston retracts to the set gap only. The compensating piston acts as a
stopper, as the oil entrapped within the cavity cannot escape through the
check valve.
Condition 2, with worn friction disc: (self adjustment at disc wear).
When discs are worn out, the net travel of piston during braking is increased
by amount more than set gap but the travel of piston is required to be constant
i.e. equal to set gap. During braking, the annular piston moves out by
pressure. The bolt pulls the compensating piston fitted with external O-ring,
allowing brake fluid to enter into the cavity behind the compensating piston
through the ball check valve. During brake release, the annular piston retracts
to the set gap only. The compensating piston acts as a stopper, as the oil
entrapped within the cavity cannot escape through the check valve. The volume
of oil entering into the cavity is proportional to amount equal to wear. Hence
due to this system, the originallno pressure position of the piston shifts by a
distance equal to the wear and the travel required for braking remains the
same.
Advantageous features
1. Smaller size master cylinderlbraking device can be used for large scale
application and multiple discs.
2. Actuation of system hydraulically.
3. Net piston travel remains constant without requiring any adjustment for
brake wear.
4. Compact & easy to assemble with no shims required for initial volume
setting.
5. No occurrence of drag leading to no rise of oil temperature & loss of
power.
6. Increase in life and improvement in performance.
, It is to be noted that the present invention is susceptible to modifications,
adaptations and changes by those skilled in the art. Such variant embodiments
employing the concepts and features of this invention are intended to be within
the scope of the present invention, which is further set forth under the
following claims:
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WE CLAIM:
I
1. An arrangement of self adjusting hydraulic brakes with piston return I
mechanism comprising of assembly of washer, bolt, screw, check valve,
compensating piston, sealing O-ring and brake piston connected with a
central housing.
2. An arrangement as claimed in claim 1, wherein the wear compensator
comprises atleast two units placed diametrically opposite on a suitable
PCD.
3. An arrangement as claimed in claim 1 or 2, wherein the position of bolt
with respect to piston is locked by means of lock washer and screw.
4. An arrangement as claimed in any of the preceding claims, wherein said
check valve comprising of ball and spring works as direction control
valve, which allows the brake fluid to flow in one direction from the brake
piston to cavity of said compensating piston.
5. An arrangement as claimed in any of the preceding claims, wherein the
set gap is maintained during assembly.
6. An arrangement as claimed in any of the preceding claims, which
operates with new friction disc such as herein described.
7. An arrangement as claimed in any of the preceding claims, which
operates with worn friction disc such as herein described.
8. An arrangement as claimed in any of the preceding claims, which is
associated with the advantageous features such as herein described.
9. An arrangement of self adjusting hydraulic brakes with piston return
mechanism substantially as herein described with reference to the
accompanying drawings.