GB2528254A

GB2528254A - Braking system for machine

Info

Publication number: GB2528254A
Application number: GB1412449.9A
Authority: GB
Inventors: Richard Kettle; Stephen Poar
Original assignee: Caterpillar Shrewsbury Ltd
Current assignee: Caterpillar Shrewsbury Ltd
Priority date: 2014-07-14
Filing date: 2014-07-14
Publication date: 2016-01-20
Anticipated expiration: 2034-07-14
Also published as: GB201412449D0; GB2528254B

Abstract

A braking system includes a brake device 114 coupled with a lever assembly 124 to cause a braking force to be applied to the machine. A first linear actuator 138, preferably a hydraulic piston/cylinder, and a second linear actuator 122, preferably a worm screw 148 driven by electric motor 146, is actuated from a retracted position to an extended position based on a first braking input, preferably a brake pedal, and a second braking input, preferably a parking switch, respectively. A lever assembly 124 is actuated by one of the first linear actuator 138 and the second linear actuator 122 to actuate the brake device 114. The lever assembly includes a first lever portion 156 configured to actuate the brake device 114 in the extended position of the first linear actuator 138. A second lever portion152 is configured to releasably engage with the first lever portion 156 to actuate the brake device 114 in the extended position of the second linear actuator 122.

Description

BRAKING SYSTEM FOR MACHINE

Technical Field

[0001] The present disclosure relates to a braking system for a machine.

Background

[0002] A typical braking system for a machine may include a hydraulic brake system and a parking brake system for separately actuating one or more brake devices of the machine. The hydraulic brake system may include a hydraulic cylinder to actuate the brake devices of the machine. The hydraulic brake system may be associated with service braking and/or emergency braking of the machine. The parking brake system may include a threaded arrangement of a rod arid a cylinder which is actuated electrically.

[0003] The combination of the hydraulic brake system and parking brake system to separately actuate the brake device may be complex and involve a multitude of components. Due to the threaded arrangement of the parking brake system, the rod and the cylinder is in a locked configuration when the parking brake system is inactive. Hence, during an actuation of the hydraulic brake system, the threaded arrangement of the parking brake system may resist free movement of the hydraulic brake system.

Summary of the Disclosure

10004] In one aspect of the present disclosure, a braking system for a machine is disclosed, The braking system includes a brake device configured to cause a braking force to be applied to the machine, A first linear actuator is configured to be actuated from a retracted position to an extended position based on a first braking input. A second linear actuator is configured to be actuated from a retracted position to an extended position based on a second braking input. A lever assembly is operatively coupled with the brake device. The lever assembly is configured for actuation by at least one of the first linear actuator and the second linear actuator so as to actuate the brake device. The lever assembly includes a first lever portion coupled to the first linear actuator. The first lever portion is configured to actuate the brake device in the extended position of the first linear actuator, A second lever portion is coupled to the second linear actuator. The second lever portion is configured to releasably engage with the first lever portion to actuate the brake device in the extended position of the second linear actuator.

[0005] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

Brief Description of the Drawings

[0006] FIG. t is a block diagram illustrating a braking system for a machine, according to an exemplary embodiment of the present disclosure; [0007] FIG. 2 illustrates a side view of a lever assembly of the braking system, according to an exemplary embodiment of the present disclosure; [0008] FIG, 3 is a perspective view of the lever assembly, according to an

exemplary embodiment of the present disclosure;

[0009] FIG, 4 is a sectional view of the lever assembly taken along line A-A' of FIG. 3; [0010] FIG. 5 is an arrangement of the lever assembly of FIG. 2 in an operational configuration; and [0011] FIG. 6 is an arrangement of the lever assembly of FIG. 2 in another operational configuration.

Detailed Description

[0012] Reference will now be made in detail to exemplary embodiments, which are illustrated with reference to the accompanying drawings. Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts.

[0013] FIG. 1 shows a block diagram illustrating a braking system 100 for a machine, according to an exemplary embodiment of the present disclosure. The machine may be an on-highway or an off-highway vehicle, For example, the machine may be a loader, a grader, an excavator, and the like, The machine may be any other type of machine associated with various industries such as construction, mining, agriculture, and transportation 100141 Further, in FIG. 1, dotted lines schematically represent electrical communications between various components of the braking system 100.

Mechanical linkages or connections between various components are schematically shown by solid lines. Moreover, hydraulic connections or flows between components are schematically shown as dash-dot lines.

100151 The braking system 00 may include a service brake system 102 for applying a braking force to the machine so as to control, decelerate and/or stop the motion of the machine. The service brake system 102 may be actuated by a brake pedal 104. The brake pedal 104 may be disposed within an operator cab of the machine, The brake pedal 104 may be operated by an operator of the machine by foot. Although the service brake system 102 is actuated based on a braking input from the operator via the brake pedal 104, it may be contemplated that the bralcing input may be communicated based on an actuation of a lever or a switch. The brake pedal 104 may include a foot rest at one end thereof and another end may be coupled to a linkage 106. The brake pedal 104 may be moveable between an inactive position and a maximum depressed position based on the braking input from the operator. The linkage 106 may be further coupled to a brake lever 108. The linkage 106 may include one or more members coupled between the brake pedal 104 and the brake lever 108 to actuate the brake lever 108 upon actuation of the brake pedal 04 from the inactive position by the operator.

[0016] The brake lever 108 may be operatively associated with a brake hydraulic system 113. In an exemplary embodiment, the brake hydraulic system 113 may include a valve (not shown) that may be configured to receive an input from the brake lever 108. The valve may be actuated between a closed position and an open position upon actuation by the brake lever 108. The valve may be normally biased to the closed position. Further, the valve may be actuated, for example, mechanically, hydraulically, pneumatically or electrically. The valve may be further fluidly coupled to a brake device 114. The brake device 114 may be operatively coupled to a ground engaging member 116 of the machine. The valve may be configured within the brake hydraulic system 113 to receive a pressurized fluid and to selectively allow or restrict flow of the pressurized fluid to the brake device 114. The valve may allow the pressurized fluid to the brake device 114 upon actuation of the valve to the open position based on a movement of the brake pedal 104 by the operator.

[0017] The brake device 114 is configured to cause a braking force to be applied to the machine. Further, the brake device 114 may be configured to be actuated between a disengaged position to an engaged position. In an exemplary embodiment, the ground engaging member 116 may be one of a plurality of wheels, The machine may include at least a pair of front wheels and at least a pair of rear wheels, Each of the pair of front 2md rear wheels may be coupled with the bralce device 114. In another exemplary embodiment, the ground engaging member 116 may include tracks.

[0018] In an exemplary embodiment, the bralce device 114 may include a plurality of rotatable discs and a plurality of stationary discs. The rotatable discs may be splined to a wheel hub for rotation therewith and the stationary discs may be connected to a stationary wheel housing, The stationary wheel housing may define a plurality of passages including a fluid supply passage to communicate with the brake hydraulic system 113. A brake piston may be disposed within the stationary wheel housing to move between a released position and a braking position, The released position of the brake piston may correspond to the disengaged position of the brake device 114 and the braking position of the brake piston may correspond to the engaged position of the brake device 114. In the braking position, the brake piston may engage rotatable discs with the stationary discs of the brake device 114, thereby applying a braking force. It may also be contemplated that that the rotatable discs and the stationary discs may also be partially engaged to apply a braking force corresponding to an intermediate position of the brake piston between the released position and the braking position. When the engine of the machine is operational, the valve, based on actuation of the brake lever 108 may allow the pressurized fluid to the fluid supply passage of the stationary wheel housing. Subsequently, the brake piston may move to the braking position to engage the rotatable discs with the stationary discs. Thus, the ground engaging member 16 associated with the brake device 114 may be restricted from rotation to decelerate or stop the machine.

[0019] The braking system 100 further includes an emergency brake system 130, according to an exemplary embodiment of the present disclosure. The emergency brake system 130 may include an accumulator 132. The accumulator 132 may be any type of accumulator such as those known in the art. The accumulator 132 may be fluidly coupled to a machine hydraulic system 118. The machine hydraulic system 118 may supply the accumulator 132 with a pressurized fluid. The machine hydraulic system 118 may any known hydraulic system of the machine, such as a steering system or an implement system.

[0020] The accumulator 132 may be frirther fluidly coupled to a first linear actuator 138. The first linear actuator 138 is configured to be actuated from a retracted position to an extended position based on a first braking input. The first braking input may correspond to movement of the brake pedal 104 between the inactive position and the maximum depressed position thereof by the operator during an emergency braking situation of the machine, The first linear actuator 138 may be further operatively coupled to a lever assembly 124. The lever assembly 124 may be operatively coupled to the brake device 114 associated with each of the pair of front wheels or rear wheels. At the maximum depressed position of the brake pedal 104, the pressurized fluid stored in the accumulator 132 may be supplied to the first linear actuator 138. The first linear actuator 138 may move to the extended position from the retracted position to actuate the lever assembly 124, and thereby apply a braking force on the brake device 114. In an exemplary embodiment, the accumulator 132 may be fluidly coupled to the first linear actuator 138 via a valve (not shown) to selectively allow the stored fluid from the accumulator 136 to the first linear actuator 138. Ihe valve may be actuated upon movement of the brake pedal 104 to the maximum depressed position, [0021] It may be contemplated that the first linear actuator 138 may also be associated with the service brake system 102. For example, the brake hydraulic system 113 may actuate the first linear actuator 138 based on a depression of the brakepedal 104.

100221 The braking system 100 of the machine may further include a parking brake system 120. The parking brake system 120 may include a second linear actuator 122 that may be operatively coupled to the lever assembly 124. The second linear actuator U2 is configured to be actuated from a retracted position to an extended position based on a second braking input. The second linear actuator 122 may be actuated by the operator electrically. The second braking input may correspond to actuation of the second linear actuator 122 through an electric switch 126. The electric switch 126 may selectively actuate the second linear actuator 122 to move to the extended position. The electric switch 126 may be disposed within the operator cab of the machine. When there is a requirement of a bralcing force to be applied while the machine is stationary, the operator may turn the electric switch 126 ON so that the second linear actuator 122 may move to the extended position and apply a braking force on the brake device 114.

[0023] FIG. 2 is a side view of the lever assembly 124 in association with the first linear actuator 138 and the second linear actuator 122, according to an exemplary embodiment of the present disclosure. The second linear actuator 122 may include a hollow cylindrical body 140 comprising a first end 142 and a second end 144. An electric motor 146 may be mounted adjacent to the first end 142 of the hollow cylindrical body 140. The electric motor 146 may be drivably coupled to a worm screw 148 that may be slidably received through the second end 144 of the hollow cylindrical body 140. The worm screw 148 may slide within the hollow cylindrical body 140 upon actuation of the electric switch 126 to actuate the second linear actuator 122 between the retracted position and the extended position. A free end of the worm screw 148 may be provided with a pin 149 to couple to a second lever portion 152 of the lever assembly 124. The lever assembly 124 may be coupled to a bralce device 114 associated with the ground engaging member 116. In an example, the lever assembly 124 disposed at the free end of the worm screw 148 may be operatively coupled to the brake device 114 associated with one of the pair of front wheel or one of the pair of rear wheels disposed at a right side of the machine. The first end 142 of the hollow cylindrical body 140 may be coupled to a second lever portion 152 of the lever assembly 124 via a pin 149. In an example, the lever assembly 124 disposed at the first end 142 of the hollow cylindrical body 140 may be operatively coupled to the brake device 114 associated with one of the pair of front wheels or one of the pair of rear wheels disposed at a left side of the machine.. Alternatively, the lever assembly 124 may be coupled to multiple brake devices 114 associated with the pair of front wheels or the pair of rear wheels of the machine.

100241 A coupling member 151 may be connected to the first end 142 of the hollow cylindrical body 140 to couple to the second lever portion 152. The coupling member 151 may be connected to the hollow cylindrical body 140 to optimize a length of the second linear actuator 122 between the two lever assemblies 124. The coupling member 151 may be a solid or a hollow member.

The second linear actuator 122 may be moved to the retracted position by moving the electric switch 126 to an OFF position. In an exemplary embodiment, moving the electric switch 126 to the OFF position may include driving the electric motor 146 in a reverse direction to the direction when moving the second linear actuator 122 to the extended position.

100251 The electric motor 146 may be in electrical communication with an electric system of the machine. The electric system of the machine may include electric power sources such as, for example, a baftery or a generator coupled to the engine for supplying electric power to the electric motor 146 to actuate the worm screw 148. Further, the electric motor 46 may be electrically coupled to the electric switch 126 to selectively actuate the electric motor 146 based on the second braking input from the operator.

100261 The first linear actuator 138 may be a hydraulic cylinder such as a single acting cylinder or a double acting cylinder. In an exemplary embodiment, the first linear actuator 138 may include a cylinder 154 and a piston (not shown) slidably disposed within the cylinder 154. The cylinder 154 may comprise a head end 158 and a rod end 160. The head end 158 of the cylinder 154 may be fluidly coupled to the accumulator 132 through a first port 162 and the rod end 160 of the cylinder 154 may be fluidly coupled to the machine hydraulic system 118 through a second port 164. The piston may be coupled to a piston rod 155 that maybe movable within the cylinder 154. Upon receipt of pressurized fluid from the accumulator 132, the piston rod 155 may slide within the cylinder 154 to cause actuation of the first linear actuator 138 between the retracted position and the extended position. A free end of the piston rod 155 may be coupled to a first lever portion 156 of the lever assembly 124. The lever assembly 124 coupled to the free end of the piston rod 155 may be operatively coupled to the brake device 114 associated with the right side of the machine. During actuation of the emergency brake system 130, the fluid stored under the predetermined pressure in the accumulator 132 may flow into the head end 158 of the cylinder 154 and thereby actuate the first linear actuator 138 to move towards the extended position. While receiving the pressurized fluid in the head end 158 of the cylinder 154, the fluid present in the rod end 60 of the cylinder 154 may flow to the machine hydraulic system 118. In an exemplary embodiment, an elastic member such as a coil spring may be disposed in the first linear actuator 138 to move the piston rod 155 to the retracted position upon release of the brake pedal 104 from the maximum depressed position.

[0027] In an exemplary embodiment, the first linear actuator 138 may further include a telescopic arrangement 166. The telescopic arrangement 166 may include a first guiding member 168 that may be connected to the head end 158 of the cylinder 154. The first guiding member 168 may be slidably disposed in a second guiding member 170. The second guiding member 170 may be coupled to the first lever portion 156 of the lever assembly 124. The lever assembly 124 coupled to the second guiding member 170 may be operatively coupled to the brake device 114 associated with the lefi side of the machine. The first guiding member 168 and the second guiding member 170 may be configured to extend and retract relative to each other.

[0028] FIG. 3 shows a perspective view of the lever assembly 124, according to an exemplary embodiment of the present disclosure. The first lever portion 156 may further include a first arm 172 and a second arm 174. The first arm 172 may be coupled to the first linear actuator 138 through a pin 157 of the first linear actuator 138 and the second arm 174 may be coupled to the brake device 114 through a link member 178. The link member 178 may be further coupled to a lever (not shown) connected to the brake device N. Further, the first lever portion 156 and the second lever portion 152 of the lever assembly 124 may be rotatably disposed on a frame 150 of the machine via a pivot pin 176. The pivot pin 176 may be integral with the frame 150 or may be separately mounted on the frame 150. The first lever portion 156 and the second lever portion 152 may be independently rotatable about the pivot pin 176. The first lever portion 156 may be rotatable between a first position and a second position. The first position of the first lever portion 156 may correspond to the disengaged position of the brake device 114 and the second position the first lever portion 156 may correspond to the engaged position of the brake device 114.

100291 The frame 150 of the machine may include a first flange W2 and a second flange 184 which are spaced apart from each other and may extend upward. The first flange 182 and the second flange 184 may be provided with holes 86 to coaxially receive the pivot pin P6 therethrough. The first lever portion 156 may define a base end 187 that may be rotatably disposed on the pivot pin 176. The first arm 172 and the second arm 174 of the first lever portion 156 may extend from the base end 187. The second lever portion 152 may also define abase end 188 that may be rotatably disposed on the pivot pin 176. Thus, both the first lever portion 156 and the second lever portion 152 may be rotatably disposed on the pivot pin 176 between the first flange 182 and the second flange 184. The second lever portion 152 may further include an engaging surface 189 that may be configured to abut a complementary surface 90 of the first lever portion 156. Further, the engaging surface 189 of the second lever portion 152 may be configured to releasably engage with the complementary surface 190 of the first lever portion 156. In the extended position of the first linear actuator 138, the first lever portion 156 may disengage from the second lever portion 152 and rotate about the pivot pin 176 to actuate the brake device 114 to the engaged position thereof In the extended position of the second linear actuator U2, the second lever portion 152 releasably engages with the first lever portion 156 to actuate the brake device 114 to the engaged position. An exemplary mounting arrangement 192 of the lever assembly 124 including the first lever portion 156 and the second lever portion 152 is described hereinafter in detail.

[0030] FIG. 4 illustrates the exemplary mounting arrangement 192 of the lever assembly 124. The base end 187 of the first lever portion 156 may include a first leg 194 and a second leg 196 spaced apart from the first leg 194. Each of the first leg 194 and the second leg 196 may be provided with holes 198. The holes 198 may coaxially receive the pivot pin 176 therethrough. Further, a washer 202 may be disposed in the hole 198 of the first leg 194 and the second leg 196 to rotatably dispose the first lever portion 156 on the pivot pin 176. The washer 202 may include a head portion 204. The washer 202 may be disposed in the holes 198 such that the head portion 204 prevents contact of the first lever portion 156 from the first and second flanges 182, 184 while disposing the first lever portion 156 between the first and the second flanges 182, 184. The base end 188 of the second lever portion 152 may be provided with a hole 206 to receive the pivot pin 176. Further, a pair of washers 208 may be disposed in the hole 206. Each of the pair of washers 208 may include a head portion 210.

[0031] The base end 188 of the second lever portion 152 may be disposed between the first and second legs 194, 196 of the first lever portion 156. Further, the hole 206 of the second lever portion 152 may be aligned with the hole 198 of the first lever portion 156 to be rotatably disposed on the pivot pin 176. The head portion 210 of the washers 208 may prevent contact between the second lever portion 152 and the first lever portion 156. The washers 202 and 208 may be used in the mounting arrangement 192 for avoiding wear and tear between the moving components, such as first lever portion 156 and the second lever portion 152, against the stationary components, such as the first and second flanges 182, 184.

[0032] In the mounting arrangement 192, the holes 198 of the first lever portion 156 and the hole 206 of the second lever portion 152 may be aligned with the hole 186 of the first flange 182 and the second flange 184. Further, the pivot pin 176 may be inserted through the holes 186 of the first and the second flanges 182,

--I I--

184 to rotatably dispose the lever assembly 124 with the frame 150 of the machine.

Industrial Applicability

[0033] A braking system for a machine includes a hydraulic brake system and a parking brake system for separately actuating one or more brake devices of the machine. The hydraulic brake system and the parking brake system may include a pair of lever assemblies to actuate respective brake devices associated with the ground engaging members at right and left sides of the machine. Each of the lever assemblies includes a first lever portion operatively coupled with a first linear actuator associated with the hydraulic brake system. Further, a second lever portion of each of the lever assemblies is operatively coupled with a second linear actuator associated with the parlcing brake system. The first lever portion and the second lever portion are independently rotatable about a pivot pin such that the hydraulic brake system is actuated independent of the position of the second linear actuator, Thus, the lever assemblies of the present disclosure may allow the hydraulic brake system to independently actuate the brake device without any resistance from the parking brake system.

[0034] The present disclosure relates to the braking system 100 including the lever assembly 124. FIG. S shows an operational configuration of the lever assembly 24. The operational configuration of the lever assembly 124, as illustrated in FIG. 5, may corespond to an actuation of the emergency brake system 130 while the parking brake system 120 is inactive. In an emergency braking situation of the machine, the operator may depress the brake pedal 104 to the maximum depressed position, At the maximum depressed position of the brake pedal 104, the linkage 106 may move the brake lever 108 to actuate the emergency brake system 130. Upon actuation of the emergency brake system 130, the pressurized fluid stored in the accumulator 132 may flow to the head end 158 of the cylinder 154 of the first linear actuator 138. While receiving the pressurized fluid from the accumulator 132, the first linear actuator 138 may move to the extended position. In the extended position, the first linear actuator 138 coupled between the first arm 172 of the first lever portion 156 may actuate the first lever portions 156 to move to the second position. In the second position of each of the first lever portions 156, the second arm 174 coupled to the link member 178 may move the brake device 114 to the engaged position.

[0035] In the extended position of the first linear actuator 138, the second linear actuator 122 coupled to the second lever portion 152 of the lever assembly 124 may remain in the retracted position. The complementary surface 190 of the first lever portion 156 may disengage from the engaging surface 189 of the second lever portion 152 and the first lever portion 156 moves to the second position independent of the second lever portion 52.

[0036] FIG. 6 shows an arrangement of the lever assembly 124 in another operational configuration. The operational configuration, as illustrated in FIG. 6, may correspond to an actuation of the parking brake system 120 while the emergency brake system 130 is inactive. For actuating the parking brake system 120, the operator may actuate the electric switch 126. Upon actuation of the electric switch 126, the second linear actuator 122 may move towards the extended position. While moving towards the extended position, the engaging surface 189 of the second lever portion 152 may engage with the complementary surface 90 of the first lever portion 156. Thus, the second lever portion b2 actuates the first lever portion 156 to move to the second position. In the second position of the first lever portion 156, the link member 178 coupled to the second arm 174 of the first lever portion 156 may actuate the brake device 114 to the engaged position.

[0037] During the actuation of the second linear actuator 122, the telescopic arrangement 166 may extend in order to allow pivotal movement of the first lever portion 156 to the second position. Thus, the parking brake system 120 may actuate the lever assembly 124 to move the brake device 114 to the engaged position. It may be apparent to a person ordinarily skilled in the art that in the extended position of the second linear actuator 122, the second lever portion 52 engages the first lever portion 156 and moves the first lever portion 156 to actuate the brake device 114 irrespective of a position of actuation of the first linear actuator 138.

[0038] The lever assembly 124 of the present disclosure may allow the first linear actuator 138 to independently actuate the brake device 114 without any resistance from the second linear actuator 122, Further, the lever assembly 124 may also enable actuation of the brake device 114 by the second linear actuator 122 irrespective of a position of actuation of the first linear actuator 138 [0039] While aspects of the present disclosure have been particularly shown and described with reference to the exemplary embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof

Claims

Claims What is claimed is: 1 A braking system for a machine, the braking system comprising a brake device configured to cause a braking force to be applied to the machine; a first linear actuator configured to be actuated from a retracted position to an extended position based on a first braking input; a second linear actuator configured to be actuated from a retracted position to an extended position based on a second braking input; and a lever assembly operatively coupled with the brake device, the lever assembly being configured for actuation by at least one of the first linear actuator and the second linear actuator so as to actuate the brake device, the lever assembly comprising: a first lever portion coupled to the first linear actuator, wherein the first lever portion is configured to actuate the brake device in the extended position of the first linear actuator; and a second lever portion coupled to the second linear actuator, wherein the second lever portion is configured to releasably engage with the first lever portion to actuate the brake device in the extended position of the second linear actuator.
2. The braking system of claim 1, wherein the first lever portion comprising a first an-n coupled to the first linear actuator and a second arm coupled to the brake device.
3, The braking system of claim I, frirther comprising a pivot pin coupled to a frame of the machine, wherein the first lever portion and the second lever portion are independently rotatable about the pivot pin.
4, The braking system of claim I, wherein the second lever portion comprises an engaging surface configured to contact a complementary surface of the first lever portion.
5. The braking system of claim 1, wherein the first lever portion is disengaged from the second lever portion when the first linear actuator is actuated from the retracted position.
6. The braking system of claim 3, wherein the second lever portion rotates the first lever portion about the pivot pin based on actuation of the second linear actuator from the retracted position thereof while the first linear actuator is in the retracted position.
7. The braking system of claim I, wherein the braking system further comprises a telescopic arrangement coupled to first linear actuator, the telescopic arrangement configured to allow the actuation of the lever assembly by the second linear actuator while the first linear actuator is in the retracted position.
8. The braking system of daim 1, wherein the first linear actuator is a hydraulic cylinder actuated by a machine hydraulic system.
9. The braking system of claim I, wherein the second linear actuator is a worm screw operated by an electric motor.
10. The braking system of claim 1, wherein the first braking input is provided by a depression of a brake pedal.

11, The braking system of claim 1, wherein the second braking input is provided by an actuation of an electric switch.