Patent Application
20110297490
This invention relates to a caliper brake. More specifically, this invention relates to such a caliper brake having an improved return spring assembly that provides an increased biasing force.
Caliper style brakes include one or more stators having friction material adhered to one side. The actuating mechanism of the brake causes the stators to selectively engage a rotor positioned adjacent thereto to cause a braking force to be applied. Often, the stators are caused to move by one or more pistons that are actuated upon introduction of a pressurized fluid, such as, for example, oil. The pistons may be returned to their original position upon removal of the pressurized fluid due to the presence of a biasing mechanism. The biasing mechanism is typically a spring positioned between the opposing stators to provide a biasing force in a direction opposite the direction of actuation, often referred to as a return spring.
In some caliper braking systems, especially those that require a relatively high braking force, such as dump trucks and other off-road vehicles, problems have been encountered with the strength of the return spring. In these instances, some residual pressure remains in the hydraulic system of the brake after the actuating mechanism is released that is not overcome by the biasing force of the return spring. Thus, the stators are not fully returned to their unactuated position and detrimentally continue to apply a braking force to the rotor. This failure to fully return the stators also results in increased wear on the friction pad of the stators, thereby requiring increased maintenance.
One attempt at improving the performance of the return spring in caliper brakes installed on heavy industrial equipment has been to simply provide a stronger spring, thereby increasing the biasing force that returns the stators to their unactuated position. However, stronger springs cannot compress as far as weaker springs, and therefore have a taller solid height (the height, or length, of the spring at complete compression). Therefore, the stators are unable to travel far enough to utilize all of the friction material secured to the stators, and must be replaced more frequently than in a caliper brake with springs having a solid height that allows for use of the entire friction pad.
Thus, the need exists for an improved caliper braking system that provides a greater return force to the stators while also allowing use of the entire friction pad.
It is thus an object of one aspect of the present invention to provide a caliper brake with an improved return spring assembly.
It is an object of another aspect of the present invention to provide a caliper brake, as above, with a return spring assembly that includes a high biasing force.
It is an object of yet another aspect of the present invention to provide a caliper brake, as above, including a mechanism for safely replacing the stators.
These and other objects of the present invention, as well as the advantages thereof over existing prior art forms, which will become apparent from the description to follow, are accomplished by the improvements hereinafter described and claimed.
In general, a caliper brake according to the concepts of the present invention includes a caliper brake having a first stator assembly, a second stator assembly spaced from the first stator assembly, and a return spring assembly, said return spring assembly including a first off-set bracket extending from the first stator assembly, a second off-set bracket extending from the second stator assembly, and a return spring positioned between the first and second off-set brackets.
In accordance with at least one aspect of the present invention, a caliper brake includes a pair of stator pins, a first stator assembly slidably positioned on the stator pins, a second stator assembly slidably positioned on the stator pins and spaced from the first stator assembly, and a return spring assembly, said return spring assembly including a first off-set bracket extending from the first stator assembly, a second off-set bracket extending from the second stator assembly, and a return spring positioned between the first and second off-set brackets, wherein a gap between the off-set brackets at the position of the return spring is greater than a gap between the off-set brackets at the point of connection to the first and second stator assemblies. A preferred exemplary caliper brake according to the concepts of the present invention is shown by way of example in the accompanying drawings without attempting to show all the various forms and modifications in which the invention might be embodied, the invention being measured by the appended claims and not by the details of the specification.
A brake made in accordance with the present invention is indicated generally by the numeral 10 and includes a housing 11 that carries and protects the operating components of brake 10. Housing 11 may include a mounting plate 12 on one side that includes a plurality of holes 14 therethrough. Brake 10 may be secured to a machine or vehicle frame by a plurality of bolts (not shown) that are inserted through holes 14 in mounting bracket 12. Brake 10 is positioned over a rotor of the machine or vehicle for selective frictional engagement therewith.
Referring now to
As will be appreciated by those skilled in the art, pistons 24 are axially movable within bores 22 to selectively apply pressure to spaced stator assemblies 32. Piston movement is caused by the introduction of pressurized fluid into a chamber 34 formed between end cap 26 and piston 24. A gasket 28 is provided around the outer periphery of each end cap 26 to prevent fluid from escaping from chamber 34. Each stator assembly 32 includes a stator plate 36 with a friction material 38 bonded thereto. As shown in
Stator assemblies 32 each include a pair of holes that are adapted to receive a stator pin 40 therethrough. The holes in the stator assemblies are aligned so that each stator pin 40 passes through both stator assemblies 32. Stator pin 40 also is received through holes or in recesses in housing 11. As will be appreciated by those skilled in the art, stator assemblies 32 are capable of axial movement along stator pins 40. Each stator assembly 32 is movable between an unactuated position, in which the pistons 24 apply little or no force to stator assemblies 32, and an actuated position, in which the stator assemblies 32 are forced toward each other by the pistons 24 until friction material 38 of the stator assemblies contacts a rotor.
Referring to
Each off-set bracket 52 includes a generally planar mounting portion 54 adjacent stator plate 36, a generally planar support portion 56, and a connecting portion 58 extending between the mounting portion 54 and the support portion 56. Connecting portion 58 may be provided in any desired form or shape, but in the embodiment shown in the drawings the connecting portion 58 is curved and rounded. Mounting portion 54 is axially displaced, in a direction parallel to the orientation of stator pins 40, from support portion 56. In addition, mounting portion 54 is laterally displaced, in a direction perpendicular to the orientation of stator pins 40, from support portion 56.
As is apparent from
Referring to
A first spring retaining member 64 is secured in the aperture 62 in a first off-set bracket 52, and a second spring retaining member 66 is secured in the aperture 62 of a second off-set bracket 52. Like apertures 62, first spring retaining member 64 and second spring retaining member 66 are generally coaxial. Both first and second spring retaining members 64 and 66 include a generally cylindrical body 68 and an outwardly extending flange 70 at one end. Spring retaining members 64 and 66 may be secured in apertures 62 by any known method. For example, retaining members 64 and 66 may be press fit in apertures 62.
First spring retaining member 64 includes a non-threaded bore 72 therein, and second spring retaining member 66 includes a threaded bore 74 therein. Bore 72 through first spring retaining member 64 and threaded bore 74 through second spring retaining member 66 are generally coaxial and are substantially aligned. Non-threaded bore 72 has a diameter that is large enough to allow a threaded bolt sized to engage threaded bore 74 to pass therethrough without significant resistance.
Compression spring 60, also referred to as a return spring, is received over first and second spring retaining members 64 and 66 and between support portions 56 of off-set brackets 52. As will be apparent to those skilled in the art, compression spring 60 provides a biasing force to stator assemblies 32 through off-set brackets 52. Any compression spring known to those skilled in the art and capable of providing the requisite biasing force may be used in return spring assemblies 50.
First and second spring retaining members 64 and 66, bore 72 and threaded bore 74 together provide a mechanism for compressing return spring 60 prior to installing or removing stator assemblies 32 from brake 10. A bolt (not shown) having a threaded end may be inserted through bore 72 in first spring retaining member 64 and may then engage threaded bore 74 in second spring retaining member 66. As will be appreciated by those skilled in the art, rotation of the bolt in a first direction will cause first and second spring retaining members and, consequently, stator assemblies 32, to move toward one another. Rotation in a second direction will cause stator assemblies to move apart. After compressing the return spring 60 on each side of the stator assemblies 32, stator pins 40 may be removed or inserted from housing 11 and stator plates 36, thereby allowing both stator assemblies 32 and the return spring assemblies 50 to be easily replaced. Removal of the threaded bolt from threaded bore 74 will allow the stator assemblies to return to their original position.
In view of the foregoing, it should thus be evident that a brake as described herein accomplishes the objects of the present invention and otherwise substantially improves the art.
