Service brake lock mechanism

Claim 2

In a vehicle having a structure supporting a brake pedal rockable forwardly about an axis from a normal brake-releasing position to a fully depressed brake-engaging position, the combination with said pedal of a locking element rockable about an axis spaced forwardly from and parAllel to the brake pedal axis and being rockable between a forward normal disengaged position, wherein it is out of engagement with the brake pedal, and a rearward locking position wherein it is in a position blocking the brake pedal from moving from said fully depressed position; a control member mounted for fore-and-aft shiftable movement; lost-motion connection means connecting said control member with said locking element such that the latter is positively shifted forwardly by forward movement of the control member; a return spring means urging said control member toward a normally released forward position wherein the control member acts through said lost-motion connection means to hold said locking element in its disengaged position; a second spring means extending between said control member and locking element and exerting a predetermined increasing force tending to rock said locking element to its locking position as said control member is moved to a rearward position; detent means for holding said control member in said rearward position; and cooperating abutment surface means on said brake pedal and said locking element for preventing the locking element from moving to said locking position until the brake pedal is moved to said fully depressed position.

Claim 3

The combination set forth in claim 1 wherein said brake pedal is connected to and acts directly on a brake valve plunger and wherein said abutment surface means are located such when the brake pedal is fully depressed and the locking element is engaged that the force acting on the pedal due to the back pressure in the brake valve engages the surface means with such force that their frictional resistance to separation is greater than the force exerted on said locking element due to the first spring means acting through the control member when the latter is released from said holding means whereby a force must be applied to the brake pedal before the locking element will be rocked to its released position by the action of the first spring means.

Claim 4

In a vehicle having supporting structure, a brake control valve fixed to the structure and including a plunger; a brake pedal being supported by the structure and connected to said plunger and pivotally mounted for rocking about a transverse axis between a normal brake-releasing position and a fully depressed brake-engaging position, the combination with the pedal and valve of a locking mechanism, comprising: a locking element being pivotally supported from said structure for rocking about an axis located forwardly of and extending parallel to the pivot axis of the brake pedal, said element being rockable between a normal disengaged position, located forwardly of the brake pedal when the latter is in its brake-releasing position, and a rearward locking position located so as to block the return of the brake pedal to its brake-releasing position when the pedal is in its fully depressed position; an elongate control member located for fore-and-aft movement in an opening extending through a bracket fixed to said structure; said control member containing a transverse opening elongated in the direction of said fore-and-aft shifting movement; a pin being carried by said locking element and captively received in said transverse opening thereby forming a lost-motion connection; a first spring means extending between the support structure and said control member and biasing the latter forwardly to a released position wherein it acts through said lost-motion connection to hold said locking element in said disengaged position; a second spring means extending between the control member and the locking element for biasing the latter towards said locking position when the control member is moved rearwardly to an engaged position; and said brake pedal and locking element having cooperating abutment surface means for preventing the movement of the locking element to said locking position until the brake pedal has moved to said fully depressed position.

Claim 5

In a vehicle having supporting structure, a brake control valve fixed to the structure and including a plunger; a brake pedal being supported by the structure and connected to said plunger and pivotally mounted for rocking about a transverse axis between a normal brake-releasing position and a fully depressed brake-engaging position, the combination with the pedal and valve of a locking mechanism, comprising: a locking element being pivotally supported from said structure for rocking about an axis located forwardly of and extending parallel to the pivot axis of the brake pedal, said element being rockable between a normal disengaged position, located forwardly of the brake pedal when the latter is in its brake-releasing position, and a rearward locking position located so as to block the return of the brake pedal to its brake-releasing position when the pedal is in its fully depressed position; an elongate control member located for fore-and-aft movement in an opening extending through a bracket fixed to said structure; said control member containing a transverse opening elongated in the direction of said fore-and-aft shifting movement; a pin being carried by said locking element and captively received in said transverse opening thereby forming a lost-motion connection; a first spring means extending between the support structure and said control member and biasing the latter forwardly to a released position wherein it acts through said lost-motion connection to hold said locking element in said disengaged position; a second spring means extending between the control member and the locking element for biasing the latter towards said locking position when the control member is moved rearwardly to an engaged position; and said brake pedal and locking element having cooperating abutment surface means for preventing the movement of the locking element to said locking position until the brake pedal has moved to said fully depressed position.

Claim 6

The combination of a service brake pedal locking mechanism for releasably locking the brake pedal in a fully depressed position corresponding to full braking force application, comprising: a brake valve including a housing fixed to a support structure and defining a depending bracket portion and containing a downwardly projecting valve plunger means located forwardly of said bracket portion; a brake pedal being pivotally connected both to said bracket portion and said plunger means by means defining transverse pivot axes, said pedal being rockable about the axis at the bracket portion between a normal brake-releasing position and a fully depressed brake-applying position; a locking element rockably dependingly supported from said structure by means of a pivotal connection defining an axis extending parallel to and located forwardly of said first-mentioned axes; said locking element and brake pedal respectively having first and second abutment surface portions tracing overlapping paths of movement; said locking element being rockable between a normal forward disengaged position; wherein the first abutment surface portion is clear of the path of movement of the second abutment surface portion, and a rearward locking position wherein said first abutment surface portion engages said second abutment surface portion when the brake pedal is in its fully depressed position; a fore-and-aft extending locking element control member extending crosswise to said pivot axes and defining a transverse opening elongated in the fore-and-aft direction; connection means joining said locking element and said control member via said opening and defining a lost-motion connection; first spring means biasing the control member forwardly to a normal released position whereat the control member acts via said lost-motion connection to hold said locking element in its forward position; said control member being shiftable rearwardly from its released position to a detented lock-engaging position; and a second spring means extending between said control member and said locking element for moving the latter to its locking position when the control member is in its lock-engaging position and the brake pedal is in its fully depressed position.

Claim 7

The combination of a service brake pedal locking mechanism for releasably locking the brake pedal in a fully depressed position corresponding to full braking force application, comprising: a brake valve including a housing fixed to a support structure and defining a depending bracket portion and containing a downwardly projecting valve plunger means located forwardly of said bracket portion; a brake pedal being pivotally connected both to said bracket portion and said plunger means by means defining transverse pivot axes, said pedal being rockable about the axis at the bracket portion between a normal brake-releasing position and a fully depressed brake-applying position; a locking element rockably dependingly supported from said structure by means of a pivotal connection defining an axis extending parallel to and located forwardly of said first-mentioned axes; said locking element and brake pedal respectively having first and second abutment surface portions tracing overlapping paths of movement; said locking element being rockable between a normal forward disengaged position; wherein the first abutment surface portion is clear of the path of movement of the second abutment surface portion, and a rearward locking position wherein said first abutment surface portion engages said second abutment surface portion when the brake pedal is in its fully depressed position; a fore-and-aft extending locking element control member extending crosswise to said pivot axes and defining a transverse opening elongated in the fore-and-aft direction; connection means joining said locking element and said control member via said opening and defining a lost-motion connection; first spring means biasing the control member forwardly to a normal released position whereat the control member acts via said lost-motion connection to hold said locking element in its forward position; said control member being shiftable rearwardly from its released position to a detented lock-engaging position; and a second spring means extending between said control member and said locking element for moving the latter to its locking position when the control member is in its lock-engaging position and the brake pedal is in its fully depressed position.

Claim 8

The combination as set forth in claim 4 wherein said first and second abutment surfaces when in engagement with each other are so located relative to the connection of the valve plunger to the brake pedal that the back pressure acting on the valve plunger when the brake pedal is fully depressed is sufficient to cause the force of frictional engagement existing between said abutment surfaces to be of a value which the force exerted by said first spring is unable to overcome when the control member is released from said detent position; whereby a force must be applied to the brake pedal to offset the back pressure force before the locking element will move to its disengaged position.