Fluid actuated brake locking mechanism

Abstract

A brake locking mechanism for heavy vehicles, adapted to be installed in existing braking systems without altering the normal operation thereof, functions to prevent involuntary movement of the vehicle, due to system failure such as air or hydraulic fluid leakage, while standing. The mechanism includes a spring biased pawl engageable with rack teeth formed on the diaphragm actuated brake rod, the pawl being operated by an air or hydraulically actuated piston associated therewith and connected into the vehicle air or hydraulic system.

What is claimed is: .[.1. In a fluid operated brake setting system for heavy vehicles including, for each wheel unit, a brake, a brake actuator chamber and a brake actuator rod reciprocated by said actuator chamber and operatively connected to the wheel unit brake; a brake locking mechanism comprising: 
     
        said pawl means from said rack teeth..]. 2. A brake locking mechanism as set forth in claim .[.1.]. .Iadd.11 .Iaddend. said coupling means comprising a crank arm pivoted within said casing; one end of said crank arm being coupled to said pawl rod to provide for reciprocation of said pawl rod in response to oscillation of said crank   
     
     
        arm; said piston means acting on the other end of said crank arm. 3. A brake locking mechanism as set forth in claim 2 said piston means being moved, upon the introduction of fluid into said cylinder chamber, from a first position to a second position to disengage said pawl means from said actuator rod; a threaded hole in the casing wall confronting the head of said piston; and an adjusting screw disposed in said hole for maintaining said piston in said second position to disengage   
     
     
        said pawl means from said actuator rod. 4. A brake locking mechanism as set forth in claim 2 said spring means acting on said other end of said crank arm, in opposition to said piston means, to normally engage said pawl means with said   
     
     
        actuator rod. 5. A brake locking mechanism as set forth in claim .[.1.]. .Iadd.11 .Iaddend. restricted passage means in said casing communicating said cylinder chamber with a fluid inlet chamber to restrict the rate of fluid flow into and out of said chamber. .Iadd. 6. In a pneumatically operated brake system for applying and releasing a wheel brake of a wheeled vehicle, said brake system being of the type including a primary air source; a brake actuator chamber; a brake actuator rod operatively connected with said brake actuator chamber and said wheel brake and mounted for reciprocating movement to apply said wheel brake in response to the pressurization of said actuator chamber from said primary air source; and foot-operated valve means for supplying air from said periphery source to said actuator chamber; the improvement consisting of an auxiliary brake setting and locking mechanism for applying as well as maintaining said brake against release, independent of the operation of said foot-operated valve means, said auxiliary brake setting and locking mechanism comprising:   (a) a casing mounted in association with said brake actuator chamber; said casing having a first passage therethrough for accommodating the reciprocating movement of said brake actuator rod and a second passage transverse to, and communicating with, said first passage;   (b) said brake actuator rod being provided with longitudinally spaced transverse rack teeth; a pawl rod supported and guided for reciprocating movement in said second passage and having pawl means at one end for engagement with said rack teeth;   (c) means on said casing defining a cylinder chamber; piston means disposed in said cylinder chamber for reciprocating movement; means coupling said piston means to said pawl rod whereby air pressure within said cylinder chamber acts upon said piston to urge said pawl rod in a first direction relative to said first passage to disengage said pawl means from said rack teeth when the said air pressure is at least equal to a predetermined amount, thereby preventing the locking of said wheel brake by engagement of said pawl rod with said brake actuator rod;   (d) spring means coupled to said pawl rod normally urging said pawl rod in a second direction opposite to said first direction to engage said pawl means with said rack teeth when the air pressure within said cylinder chamber is below said predetermined amount;   (e) means for maintaining said predetermined amount of air pressure within said cylinder chamber when said actuator chamber is pressurized from said primary air source, and   (f) means for pressurizing said actuator chamber as well as reducing the air pressure in said cylinder chamber below said predetermined amount in response to loss of air pressure from said primary air source, thereby to apply said wheel brake independent of the operation of said foot-operated valve means and lock said wheel brake in said applied position by engagement of said pawl rod with said brake actuator rod. .Iaddend..Iadd. 7. The improvement as defined in claim 6 further including means simultaneously supplying air of at least said predetermined amount of air pressure to said cylinder chamber from said primary air source during the pressurization of said actuator chamber from said primary air source; an emergency air source; and means responsive to the loss of air pressure from said primary air source below said predetermined amount to pressurize said actuator chamber from said emergency air source and enable locking engagement of said pawl rod with said brake actuator rod. .Iaddend. .Iadd. 8. The improvement as defined in claim 7 further including controllable valve means for providing said loss of air pressure from said primary air source. .Iaddend..Iadd. 9. The improvement as defined by claim 8 further including means for manually disengaging said pawl rod from said brake actuator rod. .Iaddend..Iadd. 10. In a pneumatically operated brake system for applying and releasing a wheel brake of a wheeled vehicle, said brake system being of the type including a primary air source; a brake actuator chamber; a brake actuator rod operatively connected with said brake actuator chamber and said wheel brake and mounted for reciprocating movement to apply said wheel brake in response to the pressurization of said actuator chamber from said primary air source; and foot-operated valve means for supplying air from said primary source to said brake actuator chamber; the improvement consisting of an auxiliary brake setting and locking mechanism for applying as well as maintaining said brake against release, independent of the operation of said foot-operated valve means, said auxiliary brake setting and locking mechanism comprising:   (a) means for accommodating the reciprocating movement of said brake actuator rod;   (b) means supporting and guiding a pawl rod for reciprocating movement in a direction transverse to said brake actuator rod, said pawl rod having means at one end thereof for engagement with said brake actuator rod;   (c) means defining a cylinder chamber; piston means disposed in said cylinder chamber for reciprocating movement; means coupling said piston means with said pawl rod whereby air pressure within said cylinder chamber acts upon said piston to urge said pawl rod in a first direction away from said brake actuator rod when the said air pressure is at least equal to a predetermined amount, thereby preventing the locking of said wheel brake due to engagement of said pawl rod with said brake actuator rod;   (d) spring means coupled to said pawl rod normally urging said pawl rod in a second direction opposite to said first direction, thereby to engage said pawl rod with said brake actuator rod when the air pressure within said cylinder chamber is below said predetermined amount;   (e) means maintaining said predetermined amount of air pressure within said cylinder chamber when said actuator chamber is pressurized from said primary air source, and   (f) means for pressurizing said brake actuator chamber as well as reducing the air pressure in said cylinder chamber below said predetermined amount in response to a loss of air pressure from said primary air source, thereby to apply said wheel brake independent of the operation of said foot-operated valve means and lock said wheel brake in said applied position by engagement of said pawl rod with said brake actuator rod. .Iaddend. .Iadd. 11. In a pneumatically operated brake system for applying and releasing a wheel brake of a wheeled vehicle; said brake system including a primary air source, a brake actuator chamber, a brake actuator rod operatively connected with said brake actuator chamber and said wheel brake and mounted for reciprocating movement to apply said wheel brake in response to the pressurization of said brake actuator chamber from said primary source, and foot-operated valve means for supplying air from said primary source to said actuator chamber; the improvement consisting of an auxiliary brake locking mechanism for applying as well as maintaining said brake against release, independent of the operation of said foot-operated valve means, said brake locking mechanism comprising:   (a) a casing mounted in association with said brake actuator chamber, said casing having a first passage therethrough for accommodating the reciprocating movement of said brake actuator rod and a second passage transverse to, and communicating with, said first passage;   (b) said brake actuator rod being provided with longitudinally spaced transverse rack teeth; a pawl rod supported and guided for reciprocating movement in said second passage and having pawl means at one end for engagement with said rack teeth;   (c) means in said casing defining a cylinder chamber; piston means disposed in said cylinder chamber for reciprocating movement; means coupling said piston means to said pawl rod whereby air pressure within said cylinder chamber acts upon said piston to urge said pawl rod in a first direction relative to said first passage to disengage said pawl means from said rack teeth when the said air pressure is at least equal to a predetermined amount, thereby preventing the locking of said wheel brake by engagement of said pawl rod with said brake actuator rod; and   (d) spring means coupled to said pawl rod normally urging said pawl rod in a second direction opposite to said first direction to engage said pawl means with said rack teeth when the air pressure within said cylinder chamber is below said predetermined amount. .Iaddend.