Brake responsive load transfer apparatus and method

• US 3,920,283 A
• Filed: 08/26/1974
• Issued: 11/18/1975
• Est. Priority Date: 08/26/1974
• Status: Expired due to Term

• Current Assignee: Neway Anchorlok International, Inc. (SAF-HOLLAND SE)
• Original Assignee: Strader Don S
• Inventors: Strader, Don S.
• Primary Examiner(s): Reger, Duane A.
• Application Number:
  US05/500,636
• Time in Patent Office: 449 Days
• Field of Search: 188/195 280/6R,124R,124F 303/21R,21A,22R,22A
• US Class Current: 303/198
• CPC Class Codes: B60G 17/052 Pneumatic spring characteristics B60G17/048 takes precedence ; valves per se F16K
• CPC Class Codes: B60G 2200/318 two or more axles being mounted on a longitudinal rocking or walking beam
• CPC Class Codes: B60G 2202/112 longitudinally arranged
• CPC Class Codes: B60G 2202/152 Pneumatic spring
• CPC Class Codes: B60G 2800/915 Suspension load distribution
• CPC Class Codes: B60G 5/03 the arm itself being resilient, e.g. a leafspring B60G5/053 takes precedence
• CPC Class Codes: B60T 8/1843 Arrangements for detecting air spring pressure
• CPC Class Codes: B60T 8/3285 the other fluid systems being suspension elements
• CPC Class Codes: B60T 8/349 Systems adapted to control a set of axles, e.g. tandem axles

Abstract

Load transfer apparatus for resisting the effects of brake torque on a tandem axle suspension system in a vehicle comprises air pressure apparatus adapted to inject a predetermined air pressure into an air spring over the rearmost axle whenever actuated and to relieve the pressure in the air spring whenever deactuated; and a control device adapted to sense the braking force applied to the wheels and actuate the air pressure apparatus when the braking force reaches a predetermined level. The control device also deactuates this air pressure apparatus when the braking force or speed of the vehicle drops to a predetermined level. Braking force can be measured as a function of the rate of wheel deceleration, and an anti-wheel lock control device can be employed for this purpose. Alternatively, braking force can be measured as a function of brake pressure.

Claims

1. Load transfer means for use in a vehicle comprising a tandem axle suspension system;

at least one air spring mounted over the rearmost of the tandem axles; and

anti-wheel lock control means for controlling brake pressure in response to the rate of deceleration of the vehicle wheels, said load transfer means being operably connected to the anti-wheel lock control means and the air spring and being adapted to inflate the air spring to an increased pressure to resist the effects of brake torque on the tandem axles whenever the anti-wheel lock control means becomes actuated.

2. Load transfer means as claimed in claim 1 and being further adapted to relieve the increased pressure from the air spring whenever the anti-wheel lock control means becomes deactuated.

3. Lock transfer apparatus as claimed in claim 2 wherein the tandem axles are interdependently suspended from a common pivot point between the axles on each side of the vehicle.

4. Load transfer means as claimed in claim 3 wherein the load transfer means comprises:

air reservoir means adapted to hold air under pressure;

conduit means adapted to convey pressurized air from the air reservoir means to the air spring; and

valve means in said conduit means, said valve means being adapted to normally block said conduit but being actuatable by said anti-wheel lock control means to open said conduit and permit air pressure to be applied to the air spring from the air reservoir means whenever the anti-wheel lock control means is actuated.

5. Load transfer means as claimed in claim 4 wherein the valve means is further adapted to release pressure from the air spring and block the flow of air from the air reservoir means to the air spring whenever the anti-wheel lock control means is deactuated.

6. Load transfer means as claimed in claim 5 wherein the anti-wheel lock control means becomes actuated when the rate of wheel deceleration reaches about 14-19 feet per second per second.

7. Load transfer means as claimed in claim 6 wherein the load transfer means inflates the air spring to about 50-80 psi when the anti-wheel lock control device becomes actuated;

and the load tansfer device relieves substantially all of the pressure in the air spring when the anti-wheel control device becomes actuated.

8. Load transfer means as claimed in claim 7 wherein:

the tandem axles are suspended from opposite ends of leaf springs mounted longitudinally on each side of the vehicle, said leaf springs being pivotably mounted on a transverse trunion at mid-points of the leaf springs; and

the air springs are auxiliary air springs and are maintained in a substantially deflated condition until inflated by the load transfer means.

9. Load transfer means as claimed in claim 8 wherein the valve means comprises a two-position solenoid operated valve, and the air reservoir means is pressurized by a compressor in the vehicle.

10. Load transfer means for use in a vehicle suspension system comprising tandem axles interdependently suspended from a common pivot point on each side of the vehicle;

and at least one air spring mounted over the rearmost axle, said load transfer means being adapted to counteract the effects of brake torque on the tandem axles and including;

air pressure means adapted to inflate the air spring to an increased pressure to resist the effects of brake torque on the tandem axles when actuated and to relieve the increased pressure from the air spring when deactuated; and

control means adapted to measure the rate of wheel deceleration and actuate the air pressure means when the rate of wheel deceleration increases to a predetermined level, said control means being adapted to deactuate the air pressure meanS when the rate of wheel rotation or deceleration drops to a second predetermined level.

11. Load transfer means as claimed in claim 10 wherein the air pressure means comprises:

air reservoir means adapted to hold air under pressure;

conduit means adapted to convey pressurized air from the air reservoir means to the air spring; and

valve means in said conduit means, said valve means being adapted to normally block said conduit and substantially relieve the pressure in the air spring and being actuatable by said control means to open said conduit and permit air pressure to be appplied to the air spring from the air reservoir means whenever the control means is actuated.

12. Load transfer means as claimed in claim 11 wherein:

the control means is adapted to actuate the air pressure means when the rate of wheel deceleration increases to about 14-19 feet per second per second;

the air pressure means, upon actuation, is adapted to inflate the air spring to a pressure of about 50-80 psi; and

the valve means, upon deactuation, is adapted to substantially relieve the air pressure in the air spring.

13. Load transfer means as claimed in claim 10 wherein the control means is an anti-wheel lock control means for controlling brake pressure in response to wheel deceleration.

14. Load transfer means as claimed in claim 10 wherein:

the vehicle includes anti-wheel lock control means for controlling brake pressure in response to wheel deceleration, with the anti-wheel lock control means comprising sensor means adapted to emit an electrical signal at a rate proportional to the rate of wheel rotation, a control means connected to the sensor means and adapted to compute the rate of wheel deceleration from said electrical signal and emit an electrical control signal when the rate of wheel deceleration increases to a selected level, and a brake response means operably connected to the control means and adapted to control brake response upon the receipt of an actuation signal from the control means;

the control means for the load transfer means is connected to the sensor means for the anti-wheel lock control means and is adapted to compute the rate of wheel deceleration and transmit an actuation signal to the air pressure means whenever the rate of wheel deceleration reaches a predetermined level; and

both of said control means are separately adjustable to control the point at which an actuation signal is produced by each control means.

15. Load transfer means as claimed in claim 10 wherein the tandem axles are mounted to the vehicle by means of a leaf spring suspension system and the common pivot point is between the double axles.

16. Load transfer means as claimed in claim 15 wherein the leaf spring suspension system comprises a leaf spring mounted on each side of the vehicle by means of a trunion that is mounted transversely on the underside of the vehicle, said leaf springs being mounted on the trunion at the mid-points thereof, and said tandem axles being mounted at opposite ends of the leaf springs.

17. Load transfer means for use in a vehicle comprising tandem axles interdependently suspended from a common pivot point between the axles on each side of the vehicle;

an air compressor; and

brakes, said load transfer means including;

air spring means adapted to resiliently urge the top of the rearmost of the tandem axles downwardly when inflated;

air reservoir means adapted to maintain air under pressure, said air reservoir means having inlet means adapted to receive compressed air from the compressor and outlet means adapted to deliver compressed air to the air spring means;

conduit means adapted to convey pressurized air from the outlet of the air reservoir means to the air spring means;

valve means in said conduit means, said valve means having a closed position, wherein the valve means blocks the flow of air from said air reservoir means to said air spring means, and an open position, wheRein the valve means permits air to flow from the air reservoir means to the air spring means, said valve means being normally closed; and

control means responsive to the braking force exerted by the vehicle brakes and adapted to open the valve means when the braking force reaches a predetermined level.

18. Load transfer as claimed in claim 17 wherein the control means is adapted to measure the brake pressure being applied to the vehicle brakes and open said valve means when the brake pressure reaches a predetermined level.

19. Load transfer means as claimed in claim 18 wherein the valve means is a pressure-operated relay valve, and the control means is adapted to measure brake pressure and apply a control pressure signal to the relay valve corresponding to brake pressure.

20. Load transfer means as claimed in claim 19 wherein the control means is adapted to open the relay valve when the pressure on the brakes increases to about 60 psi.

21. Load transfer means as claimed in claim 17 wherein:

the valve means is a solenoid-operated shut-off valve, said valve being normally closed and being actuatable to its open position; and

the control means are adapted to sense electronically the speed of rotation of the wheels and compute therefrom the rate of deceleration of the wheels, the control means being further adapted to actuate the solenoid operated shutoff valve when the rate of deceleration reaches a predetermined level.

22. Load transfer means as claimed in claim 21 wherein the valve means is adapted to at least partially release the air pressure from the air spring means when the valve means is in its closed position.

23. Load transfer means as claimed in claim 17 wherein the tandem axles are suspended from leaf springs longitudinally mounted on each side of the vehicle, each leaf spring being pivotably mounted to the vehicle at a common point between the axles.

24. A method for counteracting the effects of brake torque in a tandem axle suspension system in a vehicle, wherein the tandem axles are interdependently suspended from a common pivot point between the axles on each side of the vehicle and an air spring is mounted over the rearmost of the tandem axles, said method comprising the steps of:

measuring the braking force applied to the vehicle wheels;

injecting additional air in the air spring to reduce the effects of brake torque on the tandem axles whenever the braking force increases to a predetermined level; and

releasing the additional air from the air spring whenever the braking force or vehicle speed drops to a second predetermined level.

25. A method as claimed in claim 24 wherein the braking force measured is the brake torque exerted on the wheels.

26. A method as claimed in claim 24 wherein the braking force measured is the rate of wheel deceleration of the vehicle.

27. A method as claimed in claim 24 wherein the braking force measured is the brake pressure on the brakes.

28. A method as claimed in claim 24 wherein the air spring is normally maintained in a nearly deflated condition and is inflated to 50-80 psi air pressure to counteract brake torque.

29. A method as claimed in claim 28 wherein the air spring is inflated to 60-65 psi air pressure to counteract brake torque.

30. A method as claimed in claim 28 wherein the air spring in inflated to counteract brake torque whenever the rate of wheel deceleration of the vehicle reaches about 14-19 feet per second per second.

31. A method as claimed in claim 30 wherein the pressure is released from the air spring when the vehicle speed drops to about 10 miles per hour.

32. A method as claimed in claim 28 wherein the air spring is inflated to counteract brake torque whenever the brake pressure on the brakes reaches about 60 psi.