Braking System

Abstract

Disclosed is a redundant braking system for a vehicle. A controller may monitor a status of a hydraulic braking system, and during vehicle travel, automatically switch to a modulated electric braking system which is separate from the hydraulic braking system when the hydraulic braking system fails. The modulated electric braking system may utilize a brake acting on a drive shaft of the vehicle, and an operator-actuated switch may set a mode of the modulated electric braking system to a non-modulated parking brake mode.

1 . A braking system for a truck comprising:
 a hydraulic braking system on the truck, the hydraulic braking system configured to apply brake force to the truck through a first brake apparatus;   a modulated electric braking system on the truck, the modulated electric braking system being separate from the hydraulic braking system and configured to apply brake force to the truck through a second brake apparatus completely separate from the first brake apparatus; and   a control system for monitoring a status of said hydraulic braking system and automatically switching to the modulated electric braking system from the hydraulic braking system during truck travel in response to a predetermined amount of change in at least one of air pressure, hydraulic fluid level, and hydraulic fluid pressure;   wherein the first brake apparatus is not actuable by the modulated electric braking system and the second brake apparatus is not actuable by the hydraulic braking system.   
   
   
       2 . The braking system of  claim 1 , wherein the modulated electric braking system is configured to act directly on a drive shaft of the truck. 
   
   
       3 . The braking system of  claim 2 , wherein the second brake apparatus is located on an input side of a torque transfer unit. 
   
   
       4 . The braking system of  claim 1 , further comprising an operator-actuated switch for setting a mode of the modulated electric braking system to a non-modulated parking brake mode. 
   
   
       5 . The braking system of  claim 4 , wherein in the parking brake mode a mechanism of said first brake apparatus maintains a braking force to a drive shaft of the truck when electric power is removed. 
   
   
       6 . The braking system of  claim 1 , wherein the hydraulic braking system is an air over hydraulic system and wherein the automatically switching to the modulated electric braking system from the hydraulic braking system during truck travel is in response to a predetermined amount of change in air pressure in the air over hydraulic system. 
   
   
       7 . The braking system of  claim 1 , wherein the automatically switching to the modulated electric braking system from the hydraulic braking system during truck travel is in response to a predetermined amount of change in hydraulic fluid pressure in the hydraulic braking system. 
   
   
       8 . The braking system of  claim 1 , wherein the control system is adapted to prevent simultaneous operation of the hydraulic braking system and the electric braking system. 
   
   
       9 . The braking system of  claim 1 , further comprising an operator actuable switch for selecting a silent mode of vehicle operation, wherein the control system switches to the modulated electric braking system from the hydraulic braking system in response to actuation of the switch. 
   
   
       10 . The braking system of  claim 1 , wherein the predetermined amount of change is less than an amount of change associated with complete failure. 
   
   
       11 . The system of  claim 1 , wherein the automatically switching comprises disabling the hydraulic braking system. 
   
   
       12 . A braking system for a land vehicle under control of an operator comprising:
 a hydraulic braking system configured to apply brake force through a first brake apparatus;   an electric braking system separate from the hydraulic braking system and configured to apply modulated brake force through a second brake apparatus completely separate from the first brake apparatus;   an operator actuated switch for switching the vehicle to a silent mode of operation; and   a controller for switching from the hydraulic braking system to the modulated electric braking system responsive to actuation of the switch during vehicle travel,   wherein the controller is adapted to allow simultaneous operation of the hydraulic braking system and the electric braking system during vehicle travel.   
   
   
       13 . The system of  claim 12 , wherein the simultaneous operation occurs when the vehicle is in a mode other than the silent mode. 
   
   
       14 . The system of clam  12 , wherein the land vehicle is a truck. 
   
   
       15 . A system for braking a truck, the system comprising:
 a foot brake pedal configured to receive a continuously variable force applied to the foot brake pedal;   converting means operatively coupled to the foot brake pedal for converting the continuously variable force to an electronic signal of a magnitude varied in response to a position of the foot brake pedal;   a brake force apparatus located on an input side of a torque transfer unit and configured to apply brake force directly to a drive shaft of the truck, the brake force apparatus including a disc brake attached directly to the drive shaft; and   a control unit configured to control the brake force apparatus to apply continuously variable modulated brake force to the drive shaft of the truck via the disc brake in an amount responsive to a travel distance of the brake pedal.   
   
   
       16 . The system of  claim 15 , further comprising an operator actuated switch for switching the truck to a silent mode of operation. 
   
   
       17 . The system of  claim 15 , further comprising a finger-actuated button accessible to a driver of the vehicle, the button configured to set a mode of the system to a non-modulated parking brake mode in which the control unit causes the brake force apparatus to apply and maintain a constant parking brake force to the drive shaft via the disk brake, the parking brake force being maintained at a constant level even if the truck is powered off. 
   
   
       18 . The system of  claim 15 , wherein the brake force is proportional to the travel distance of the brake pedal. 
   
   
       19 . The system of  claim 15 , further comprising a hydraulic brake system configured to apply braking force through a separate brake force apparatus at wheels of the truck. 
   
   
       20 . The system of  claim 15 , further comprising a finger-actuated switch adapted to enter the vehicle into a silent mode of operation, the control unit configured to control the brake force apparatus in response to actuation of the finger-actuated switch.