VEHICLE SUSPENSION SYSTEM

• US 3,773,346 A
• Filed: 01/03/1972
• Issued: 11/20/1973
• Est. Priority Date: 01/03/1972
• Status: Expired due to Term

• Current Assignee: Gary D. Swinney, James K. Scheublein
• Original Assignee: Gary D. Swinney, James K. Scheublein
• Inventors: Scheublein, James K., Swinney, Gary D.
• Primary Examiner(s): Goodman, Philip
• Application Number:
  US05/215,037
• Time in Patent Office: 687 Days
• Field of Search: 280/124R 267/60,180,166
• US Class Current: 280/124.101
• CPC Class Codes: B60G 11/00 Resilient suspensions characterised by arrangement, location or kind of springs single wheel suspension by pivoted arm resilient in itself B60G3/00; adjusting spring characteristic B60G17/00; springs per se F16F
• CPC Class Codes: B60G 17/00 Resilient suspensions having means for adjusting the spring or vibration-damper characteristics, for regulating the distance between a supporting surface and a sprung part of vehicle or for locking suspension during use to meet varying vehicular or surface conditions, e.g. due to speed or load levelling or stabilising systems for tippers B60P1/045

Abstract

A vehicle suspension system which incorporates a novel variable rate rear suspension spring having two effective stages arranged such that the natural frequency will increase or decrease substantially the same amount as the natural frequency of the front suspension system will increase or decrease when load is added or removed. The rear suspension spring includes a first stage which combines both a constant pitch section and an increasing pitch section, and a second stage which comprises only the constant pitch section. The suspension system embodying the rear suspension springs of the foregoing character operates to maintain the front suspension natural frequency substantially equal to the rear suspension natural frequency under all loading conditions.

Claims

1. In a vehicle, a frame having a principal suspension system consisting of a front wheel set, first resilient spring means operably connecting said front wheel set to the vehicle frame, a rear wheel set, second resilient spring means operably connecting said rear wheel set to the vehicle frame, said frame supporting an applied load of a variable amount and disposition relative to said front and rear wheel sets, said first resilient spring means having a natural frequency which varies with the vehicle loading amount and disposition conditions, and said second resilient spring means having a natural frequency varying with the variations of said first resilient spring means such that the natural frequencies of said first and second resilient spring means remain substantially balanced with the loading conditions.

2. The suspension system of claim 1 wherein said second resilient spring means include sections having a constant pitch and other sections having a variable pitch.

3. The suspension system of claim 1 wherein the vehicle has its center of gravity between said front and rear wheel sets, and said second resilient spring means has a variable rate operative in relation to said first resilient spring means to maintain a substantially balanced system for a variety of loads applied to the vehicle adjacent said rear wheel set.

4. A suspension assembly for a vehicle consisting of a front wheel set connected to the vehicle ahead of the center of gravity and a rear wheel set connected to the vehicle behind the center of gravity, front coil suspension spring means connecting said front wheel set to the vehicle, said front coil springs having a constant rate K1, rear coil suspension spring means connecting said rear wheel set to the vehicle, said rear coil springs having a variable rate K2, and said front and rear coil suspension springs having substantially equal natural frequencies for changes in the loading of the vehicle and said real coil suspension springs having a spring rate that varies with load applied to the vehicle.

5. In a vehicle suspension system, a longitudinal frame having a normal load center of gravity, front and rear wheels for said frame, principal suspension means connecting said front wheels to the foreport of said frame a predetermined distance L1 from the center of gravity and having a substantially Constant rate K1, and principal coil suspension springs connecting said rear wheel to the rear part of said frame a predetermined distance L2 from the center of gravity, said principal coil suspension springs having a portion of the coils formed with a constant pitch and another portion with an increasing pitch such that the rate K2 of said suspension springs increases with applied load according to the formula K2 K1 ((L1 + L2 + b) W + L1 p )/(L2 p - bW)

6. In a vehicle, a longitudinal body frame, front supporting wheels resiliently connected to the forepart of said body frame, said resilient connection of said front wheels comprising principal coil springs having a substantially constant rate, rear wheels for said body frame, principal coil suspension springs operatively connected between said rear wheels and the rear part of said body frame, said rear wheel coil springs having a linear increasing pitch for certain of its coils and constant pitch for certain others of its coils such that the rate of said coil springs varies in a manner to maintain the front and rear portion of said body frame in balance under all loading conditions, and said vehicle having the center of gravity, due to normal load only, located a distance L1 from the front wheels, the rear wheels located a distance L2 from the center of gravity, the front wheel coil springs having a constant rate K1, the rear wheel coil springs having a variable rate K2, and the rate K2 increasing with load in accordance with the relation K2 K1 ((L1 + L2 + b) W + L1 p )/(L2 p - bW)