FIELD OF INVENTION
This invention relates to a system for hydraulic annular piston brakes with 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.
BACKGROUND/PRIOR ART
Return mechanism pulls back the piston to it's original/no pressure positions,
after the removal of pressure applied through foot pedal/braking device and
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 of conventional system.
The conventional brake piston return mechanism used in earth movmg
machines or tractor is shown in fig. 1. It includes plate spring to return the
piston 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.
DRAWBACKS OF THE EXISTING SYSTEM ARE AS FOLLOWS:-
1. This system is difficult to assembly.
2. It requires shims to maintain the initial volume/pedal position.
3. Requirement of large size master cylinder/braking device as thevolume
displaced continuously increases with wear.
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0BJECTS OF THE INVENTION
The primary object of the present invention is to provide a system for hydraulic
annular piston brakes with 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 a system for hydraulic
annular piston brakes with 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 a system for hydraulic
annular piston brakes with 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 a system for hydraulic
annular piston brakes with self adjustment and return mechanism for earth
moving machines and tractors which is efficient.
Yet another object of the present invention is to provide a system for hydraulic
annular piston brakes with self adjustment and return mechanism for earth
moving machines and tractors which provides both mechanisms.
STATEMENT OF INVENTION
According to this invention, there is provided a system for hydraulic annular
piston brakes with self adjustment and return mechanism for earth moving
machines and tractors, comprising of a pm with spring mounted on a
mounting plate, wherein a gap is maintained between sleeve of the pin and pin
and a bush is provided into the pin.
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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 brake piston return system for earth moving
machines or tractors.
Fig. 2 shows :Novel system of the present invention.
Fig. 3 shows: Self adjusting units with mounting plate.
Fig. 4 shows: Self adjustment at no Disc wears.
Fig. 5 shows: Self adjustment after Disc wears.
DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH REFERENCE
TO THE ACCOMPANYING DRAWINGS:
This present invention discloses a system for hydraulic annular piston brakes
with self adjustment and return mechanism for earth moving machines and
tractors.
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 &
piston so as to avoid drag. Drag is continuous undesirable application of
brakes, leading to loss of power & high temperature.
Reference may be made to fig. 2.The present invention comprises assembly of
pin, bush, mounting plate, spring, sleeve, spacer, washer, circlip& piston on
the mounting plate (as shown in fig. 3).
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As shown in fig. 2, a pin accommodated in a sleeve is mounted on a mounting
plate together with spring. A washer is provided on the pin maintaining a gap
of (A) between the sleeve and pin.
Further, at other end, spacer is provided ·and washer with circlip is provided on
other side of the mounting plate. Again, a bush is provided into the pin.
Whole of the above assembly is mounted on piston by means of the bush.
Again, the complete assembly is mounted on retainer plate.
For this assembly, all parts are fitted as per sequence, spring is compressed,
set gap -A is maintained and circlip is fitted to make a subassembly. Further,
bush is press fitted into pin to complete the system. As principle, force required
to press fit the bush is at least 5 times the spring force of return mechanism.
This system is mounted on piston, wherein bush is fitted and acts as
connecting link between piston & pin. This complete assembly is then mounted
on bearing retainer.
Condition 1, with new friction disc: (self adjustment at no disc wear as shown
in fig. 4).When braking force is applied, the piston travel is equal to set gap and
pin connected through bush, moves along with same distance. After removal of
braking force, piston returns back to its original position by the spring force of
return mechanism and set gap A is again maintained.
Condition 2, with worn friction disc: (self adjustment at disc wear as shown in
fig. 5). 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. Pin movement is restricted by mounting plate
& is not allowed to move beyond set gap. As the force applied on piston is large,
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it pulls the bush from the pin. Bush changes its position on pin & shifts by
amount equal to wear t~ward piston movement. After removal of braking force
piston return back along with the pin to their set gap position. Hence due to
this system, the original/no pressure position of the piston shifts by a distance
equal to the wear and travel required for braking remains the same.
Advantageous features
1. Smaller size master cylinder /braking device can be used for large scale
application and multiple discs.
2. Net piston travel remains constant without requiring any adjustment for
brake wear.
3. Compact & easy to assemble with no shims required for initial volume
setting.
4. No occurrence of drag leading to no rise of oil temperature & loss of
power.
5. 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:-

WE CLAIM:
1. A system for hydraulic annular piston brakes with self adjustment and
return mechanism for earth moving machines and tractors comprising of
a pin with spring mounted on a mounting plate, wherein a gap is
maintained between sleeve of the pin and pin and a bush is provided into
the pin.
2. A system for hydraulic annular piston brakes as claimed in claim 1,
wherein the system is mounted on a piston, wherein the bush
constitutes a connecting means between the piston and pin.
3. A system for hydraulic annular piston brakes as claimed in claim 1 or 2,
wherein the gap is maintained by means of a washer on the pin.
4. A system for hydraulic annular piston brakes as claimed in any of the
preceding claims, wherein spacer is provided on one side and washer
with circlip is provided on other side of the mounting plate.
5. A system for hydraulic annular piston brakes as claimed in any of the
preceding claims, wherein the complete assembly is mounted on a
retainer plate.
6. A system for hydraulic annular piston brakes as claimed in any of the
preceding claims, wherein the system comprising of self adjustment at no
disc wear (fig. 4) and self adjustment at disc wear (fig. 5) such as herein
described.
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7. A system for hydraulic annular piston brakes as claimed in any of the
preceding claims, is associated with the advantageous features such as
herein described.
8. A system for hydraulic annular piston brakes with hydraulically operated
self adjustment and return mechanism for earth moving machines and
tractors substantially as herein described with reference to the
accompanying drawings.