Fifth wheel unit

Claim 2

A fifth wheel unit for coupling a trailer having a king pin to a tractor provided with a fluid operated braking system; said fifth wheel unit comprising: a base mounted on the tractor; a bearing having a first race secured to the base, a second race, and rolling elements interposed between the races so that the second race rotates freely with respect to the first race; upper mounting means secured to the second race; a skid plate mounted on the upper mounting means and providing a surface on which the front of the trailer rests; latching means on the skid plate for engaging the king pin and retaining the front of the trailer on the skid plate; a locking pin mounted on the skid plate and being shiftable between retracted and extended positions, the locking pin when in the retracted position being disposed below the trailer supporting surface of the skid plate and when in the extended position projecting above the skid plate to engage the trailer so as to prevent rotation of the trailer relative to the skid plate; means coupling the latching means and the locking pin for retracting the locking pin when the latching means is open; brake means between the base means and the upper mounting means for retarding rotation of the skid plate when aPplied; and control means responsive to the pressure in the fluid operated braking system for actuating the brake means when pressure within the braking system reaches a predetermined magnitude.

Claim 3

A fifth wheel unit for coupling a trailer having a king pin to a tractor, said fifth wheel unit comprising: a base secured to the tractor; a bearing having a hollow interior and including a first race secured to the base, a second race positioned opposite the first race, and rolling elements interposed between the two races to enable the second race to rotate freely relative to the first race; upper mounting means secured to the second race; a skid plate secured to and carried by the upper mounting means and providing an upwardly presented surface on which the front end of the trailer rests, the skid plate having a hole for reception of the trailer king pin and an entrance slot leading from the periphery of the skid plate to the hole; latching means carried by the skid plate and including a latch which normally projects across the entrance slot and closes the hole in the skid plate so that the king pin will not leave the hole, and a release lever for moving the latch away from its closed position; locking means carried by the skid plate and including a retractable locking pin which normally projects upwardly beyond the skid plate and into the trailer to prevent relative rotation between the trailer and the skid plate, the locking means further including operating means for retracting the locking pin completely from the trailer, the operating means being disposed in the path of the release lever so that it is shifted by the release lever and retracts the locking pin when the release lever moves the latch to its open position; and at least one brake cylinder positioned within the hollow interior of the bearing, the cylinder when expanded being engaged with both the base and the upper mounting means to prevent relative rotation between the skid plate and the tractor.

Claim 4

A fifth wheel unit for coupling a trailer having a king pin to a tractor, said fifth wheel unit comprising: a base secured to the tractor; a bearing having a hollow interior and including a first race secured to the base, a second race positioned opposite the first race, and rolling elements interposed between the two races to enable the second race to rotate freely relative to the first race; upper mounting means secured to the second race; a skid plate secured to and carried by the upper mounting means and providing an upwardly presented surface on which the front end of the trailer rests, the skid plate having a hole for reception of the trailer king pin and an entrance slot leading from the periphery of the skid plate to the hole; latching means carried by the skid plate and including a latch which normally projects across the entrance slot and closes the hole in the skid plate so that the king pin will not leave the hole, and a release lever for moving the latch away from its closed position; locking means carried by the skid plate and including a retractable locking pin which normally projects upwardly beyond the skid plate and into the trailer to prevent relative rotation between the trailer and the skid plate, the locking means further including operating means for retracting the locking pin completely from the trailer, the operating means being disposed in the path of the release lever so that it is shifted by the release lever and retracts the locking pin when the release lever moves the latch to its open position; and at least one brake cylinder positioned within the hollow interior of the bearing, the cylinder when expanded being engaged with both the base and the upper mounting means to prevent relative rotation between the skid plate and the tractor.

Claim 5

A fifth wheel unit according to claim 2 wherein the operating means includes an operating lever engaged with the locking pin for moving the locking pin as it shifts, a portion of the operating lever being disposed in the path of the release lever so that the release lever will engage and shift the operating lever as the release lever moves the latch to its open position; the operating lever when being shifted by the release lever retracting the locking pin.

Claim 6

A fifth wheel unit according to claim 3 wherein the operating lever pivots about an axis fixed relative to the skid plate and located intermediate the portion thereof engaged with the locking pin and the portion thereof which is engaged by the release lever.

Claim 7

In combination with a tractor having a fluid operated brake system including road wheel brakes, fluid lines leading to the road wheel brakes, and means for increasing the fluid pressure in the fluid lines to actuate the road wheel brakes at both normal and high braking pressures, an improved fifth wheel unit for coupling a trailer having a king pin to the tractor to prevent the trailer from jackknifing, said fifth wheel unit comprising: a base mounted rigidly on the tractor, a skid plate carried by the base and providing an upwardly presented surface on which the front of the trailer rests, the skid plate further having a hole for receiving the king pin of the trailer; a bearing between the base and the skid plate for permitting the skid plate to rotate relative to the base about a vertical axis which is fixed with respect to the base; means for locking the tractor to the skid plate for preventing the trailer from rotating relative to the skid plate; a fifth wheel brake between the base and the skid plate for impeding rotation of the skid plate on base when actuated, the fifth wheel brake being fluid operated and serving to impede rotation only when high pressure fluid is admitted to it; a fifth wheel fluid line interconnecting the brake system of the tractor and the fifth wheel brake; a valve in the fifth wheel fluid line for admitting high pressure fluid from the tractor brake system to the fifth wheel fluid line to actuate the fifth wheel brake; and means for sensing the pressure in the fluid lines leading to the road wheel brakes and for causing the valve to open when the pressure reaches a prescribed magnitude generally coresponding that encountered in panic stop situations, whereby during a panic stop the fifth wheel brake will operate and prevent the trailer form jackknifing.

Claim 8

In combination with a tractor having a fluid operated brake system including road wheel brakes, fluid lines leading to the road wheel brakes, and means for increasing the fluid pressure in the fluid lines to actuate the road wheel brakes at both normal and high braking pressures, an improved fifth wheel unit for coupling a trailer having a king pin to the tractor to prevent the trailer from jackknifing, said fifth wheel unit comprising: a base mounted rigidly on the tractor, a skid plate carried by the base and providing an upwardly presented surface on which the front of the trailer rests, the skid plate further having a hole for receiving the king pin of the trailer; a bearing between the base and the skid plate for permitting the skid plate to rotate relative to the base about a vertical axis which is fixed with respect to the base; means for locking the tractor to the skid plate for preventing the trailer from rotating relative to the skid plate; a fifth wheel brake between the base and the skid plate for impeding rotation of the skid plate on base when actuated, the fifth wheel brake being fluid operated and serving to impede rotation only when high pressure fluid is admitted to it; a fifth wheel fluid line interconnecting the brake system of the tractor and the fifth wheel brake; a valve in the fifth wheel fluid line for admitting high pressure fluid from the tractor brake system to the fifth wheel fluid line to actuate the fifth wheel brake; and means for sensing the pressure in the fluid lines leading to the road wheel brakes and for causing the valve to open when the pressure reaches a prescribed magnitude generally coresponding that encountered in panic stop situations, whereby during a panic stop the fifth wheel brake will operate and prevent the trailer form jackknifing.

Claim 9

The structure according to claim 5 wherein the means for sensing the pressure in the fluid lines leading to the road wheel brakes includes a pressure sensitive switch in one of the fluid lines leading to the road wheel brakes, and the valve is electrically operated and in series with the pressure sensitive switch.

Claim 10

The structure according to claim 5 wherein the locking means includes a pin mounted on the skid plate and movable axially between extended and retracted positions, the pin when in its extended position projecting above the upwardly presented surface of the skid plate and into a hole in the trailer and when in its retracted position being disposed below the upwardly presented surface.

Claim 11

The stucture according to claim 7 wherein the skid plate has an entrance slot sized to accommodate the trailer king pin and leading from the periphery of the skid plate to the hole; wherein the skid plate carries latching means for blocking the end of the entrance slot so as to prevent the king pin from leaving the hole by way of the entrance slot, the latching means being retractable from the end of the entrance slot to permit the trailer to be detached from the fifth wheel unit; and wherein operating means for retracting the locking pin is actuated by the latching means and causes the locking pin to retract when the latching means retracts from the end of the entrance slot.

Claim 12

A fifth wheel unit for coupling a trailer having a king pin to a tractor; said fifth wheel unit comprising: a base secured firmly to the tractor; a bearing mounted on base with its axis of rotation vertical, the bearing having a hollow interior and including a lower race secured to the base, an upper race rotatable on the lower race, and rolling elements interposed between the two races to enable the upper race to rotate freely on the lower race, the races being inseparable in the axial direction; a mounting member secured to and extended across the upper race of the bearing to close to bearing interior and having a flat surface presented toward the interior of the bearing; a skid plate mounted on the mounting member and providing an upwardly presented surface on which the front end of the trailer rests, the skid plate having an opening which receives the king pin on the trailer; locking means carried by the skid plate for locking the trailer to the skid plate so that the skid plate will not rotate relative to the trailer about the axis of the king pin, the locking means being movable in the vertical direction between an extended position wherein it projects above the surface on the skid plate and will engage the trailer and a retracted position wherein it is disposed below the upwardly presented surface on the skid plate and will be disengaged from the trailer; and at least one brake cylinder within the hollow interior of the bearing and mounted firmly on the base with its axis parallel to but offset from the axis of rotation for the bearing, the cylinder carrying a friction surface which is presented toward the flat surface on the upper mounting member and is driven tightly against the flat surface when high pressure fluid is admitted to the brake cylinder, whereby the brake cylinder will impede rotation of the skid plate and trailer relative to the tractor.

Claim 13

A fifth wheel unit for coupling a trailer having a king pin to a tractor; said fifth wheel unit comprising: a base secured firmly to the tractor; a bearing mounted on base with its axis of rotation vertical, the bearing having a hollow interior and including a lower race secured to the base, an upper race rotatable on the lower race, and rolling elements interposed between the two races to enable the upper race to rotate freely on the lower race, the races being inseparable in the axial direction; a mounting member secured to and extended across the upper race of the bearing to close to bearing interior and having a flat surface presented toward the interior of the bearing; a skid plate mounted on the mounting member and providing an upwardly presented surface on which the front end of the trailer rests, the skid plate having an opening which receives the king pin on the trailer; locking means carried by the skid plate for locking the trailer to the skid plate so that the skid plate will not rotate relative to the trailer about the axis of the king pin, the locking means being movable in the vertical direction between an extended position wherein it projects above the surface on the skid plate and will engage the trailer and a retracted position wherein it is disposed below the upwardly presented surface on the skid plate and will be disengaged from the trailer; and at least one brake cylinder within the hollow interior of the bearing and mounted firmly on the base with its axis parallel to but offset from the axis of rotation for the bearing, the cylinder carrying a friction surface which is presented toward the flat surface on the upper mounting member and is driven tightly against the flat surface when high pressure fluid is admitted to the brake cylinder, whereby the brake cylinder will impede rotation of the skid plate and trailer relative to the tractor.

Claim 14

A fifth wheel unit according to claim 9 wherein the locking means includes a pin which is oriented with its axis extended vertically and shifts between its extended and retracted positions in the direction of its vertical axis.