US3838624A — Hydraulic steering brake for tractor

Claim 1

Independent Claim 333 words

A hydraulic steering brake for a tractor having a brake pedal or steering lever, a linkage connected to said lever or pedal at one end thereof, a source of hydraulic pressure, and a brake lever engaged with a brake band, said brake comprising: a control valve means connected through said linkage to said steering lever or brake pedal for controlling the steering brake by the operation of said lever or pedal, and a hydraulic cylinder means connected to said control valve means and to the steering brake for operating the brake lever connected to the brake band of said steering brake, and wherein said control valve means comprises: a hollow valve body including a first port formed at the middle portion thereof, said first port communicating with said source of hydraulic pressure, second and third ports formed at both sides of said first port, and first and second drain ports formed at both both side ends thereof, wherein said first port communicates with the second port through a first passage formed in said valve means, a first hollow spool axially slidable within said hollow valve body for controlling said second port, a rod axially slidably fixed to said first spool, said rod having a stepped portion formed at the middle portion thereof in engagement with the end of said first spool, a first resilient member disposed inside said first spool around said rod for urging said first spool against the axial movement of said first spool and said rod, a second spool axially slidably fixed to said hollow valve body engaged at one end thereof with said first resilient member and including an intermediate landing formed thereon for controlling said third port, said second spool having an end recess portion formed at the other end thereof, and a second resilient member disposed inside of said hollow valve body around the end recess portion of said second spool for urging said second spool against the axial movement of said first spool and said rod.

Claim 2

Dependent Claim 333 words

A hydraulic steering brake for a tractor having a brake pedal or steering lever, a linkage connected to said lever or pedal at one end thereof, a source of hydraulic pressure, and a brake lever engaged with a brake band, said brake comprising: a control valve means connected through said linkage to said steering lever or brake pedal for controlling the steering brake by the operation of said lever or pedal, and a hydraulic cylinder means connected to said control valve means and to the steering brake for operating the brake lever connected to the brake band of said steering brake, and wherein said control valve means comprises: a hollow valve body including a first port formed at the middle portion thereof, said first port communicating with said source of hydraulic pressure, second and third ports formed at both sides of said first port, and first and second drain ports formed at both both side ends thereof, wherein said first port communicates with the second port through a first passage formed in said valve means, a first hollow spool axially slidable within said hollow valve body for controlling said second port, a rod axially slidably fixed to said first spool, said rod having a stepped portion formed at the middle portion thereof in engagement with the end of said first spool, a first resilient member disposed inside said first spool around said rod for urging said first spool against the axial movement of said first spool and said rod, a second spool axially slidably fixed to said hollow valve body engaged at one end thereof with said first resilient member and including an intermediate landing formed thereon for controlling said third port, said second spool having an end recess portion formed at the other end thereof, and a second resilient member disposed inside of said hollow valve body around the end recess portion of said second spool for urging said second spool against the axial movement of said first spool and said rod.

Claim 3

Dependent Claim 196 words

The hydraulic steering brake of claim 1, wherein said hydraulic cylinder means comprises: a cylinder body, a partition wall for dividing said body into front and rear chambers, a piston axially slidably disposed within said front chamber, a piston rod connected at one end thereof to said piston, said piston rod passing through said partition wall and said valve body and connected to the end of said brake lever, a first chamber formed between said partition wall and said piston, said first chamber communicating with the third port of said control valve means through a second passage, a free piston slidably axially disposed within said rear chamber on said piston rod, said free piston having an axial projection integrally projected therefrom and passing through said partition wall, said free piston forming a second chamber between the partition wall and said free piston which communicates with said second port of said control valve through a third passage formed in said body, a third resilient member axially mounted between said free piston and said cylinder body, and a fourth resilient member mounted between said free piston and the middle portion of said piston rod within said cylinder body.

Claim 4

Dependent Claim 138 words

A hydraulic steering brake for a tractor according to claim 2, wherein said control valve means further comprises: a hollow end landing formed at one end of said second spool, a fifth resilient member axially disposed within the hollow end landing, an inside spool slidably disposed into the hollow end landing of said second spool urged by said fifth resilient member against the axial movement of said rod on one side and pushed by said rod on the other, thereby urging said second spool to connect said third port with said first port, which communicates with the source of hydraulic pressure whereby said piston disposed in the front chamber of said hydraulic cylinder means operates said steering brake through said piston rod connected to said pistion against the tension of said fourth resilient member of said cylinder means.

Claim 5

Dependent Claim 138 words

A hydraulic steering brake according to claim 2, wherein said control valve means further comprises: a hollow end recess portion formed at the rear end of said second spool, a fourth passage formed at the middle portion landing of said second spool for connecting said third port of said valve body with the inside of the hollow end recess portion of said second spool, and a packing seal disposed within said hollow end recess portion of said second spool supported by said valve body at the rear end thereof to form a third chamber therein for increasing the hydraulic pressure in said third port which communicates with the first chamber of said hydraulic cylinder means, the increase in hydraulic pressure being proportional to the axial movement of said rod thereby enhancing the braking force of said steering brake.

Claim 6

Dependent Claim 70 words

The hydraulic steering brake according to claim 2, wherein a cutout is formed at the outer peripheral end of said first spool to drain the second port of said valve body which communicates with the first port which communicates with the third port which communicates with the second chamber of said cylinder means, thereby urging said piston to operate said steering brake against the tension of said fourth resilient member.

Claim 7

Dependent Claim 50 words

A hydraulic steering brake according to claim 2, further comprising a manual pump connected to the middle portion of said second passage between the second port and said second chamber of said hydraulic cylinder means to raise the hydraulic pressure of said second chamber to manually release said steering brake.

Claim 8

Dependent Claim 43 words

A hydraulic steering brake according to claim 5, further comprising a sensor provided on said cylinder body of said hydraulic cylinder means, and a warning means connected to said sensor for warning of excessive wear of the brake lining of said steering brake.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1977-09-30	1978-04-01	1978-10-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1981-09-30	1982-04-01	1982-10-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1985-09-30	1986-04-01	1986-10-01	$7700.00	Window Closed / Lapsed

Hydraulic steering brake for tractor

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