Tractor Chassis and Cab Suspension System

1. Field of the Invention

This invention concerns tractor vehicle cab suspension embodiments.

More specifically, a tractor cab suspension system where an operator's cab or alternatively an operator's work station platform in tractors without cabs, is integrally attached to the front portion sheet metal of the tractor and the entire superstructure assembly is pivotally mounted to the forward portion of the tractor running gear frame. The rear portion of the integrated cab and front sheet metal is suspended on a coil spring. A pair of vertical guide members are bolted, welded or otherwise fastened to the vertical walls of the cab floor extension to limit lateral movement of the integrated assembly while allowing vertical movement of the rear section on an arc generated around the front pivot point. A centering spreader is fastened to the rear section of the tractor running gear frame. The centering spreader is located between the vertical guide members.

2. Description of the Prior Art

It is known in the highway truck art to provide suspended cabs for improved ride. These cabs may be pivotally mounted at the front thereof to the vehicle frame and may also be provided with a coil spring suspension system at the back section of the cab.

In the tractor art, which has more stringent and diverse cab suspension problems (vis-a-vis highway trucks) due to the general roughness of the supporting terrain, when contrasted to the relatively smooth highway environment of trucks, it appears that emerging technology to provide more comfortable operator environments is being centered around the suspension of the cab or operator's work area only. Generally, a three or four point cab mounting system is provided. Coil spring and shock absorber systems are seen as onealternative to a diverse spectra of designs. One difficulty with these designs may often be the uncontrolled lateral deflection of the cab in a roll over due to the magnitude of suspension travel allowed in these designs. This problem is not present in the instant invention as the lateral movement of the cab is restricted by the interaction of the vertical guide members and the centering spreader while horizontal cab deflection is restricted through the relatively close tolerance of the suspended superstructure at the forward pivot point on the front of the vehicle at the frame.

Another problem with prior art tractor vehicles having the superstructure spring mounted above the vehicle frame and running gear is that it is difficult to maintain a sealed relationship between the inside of the floating hood and the top and sides of the radiator as these parts separate. Current designs require an expandable dam, usually a rubber bellows, to maintain this sealed arrangement. This problem doesn't exist with the design herein described as the inner surface of the hood sheet moves only a small distance on an arcuate path around the front pivot point. The conventional air directing partitions of current production tractors would flex sufficiently to accomodate this insignificant displacement between the inside of the hood and the top and sides of the heat exchanger.

Furthermore tractor vehicles are known that have integrated cab and front sheet metal sections suspended over the vehicle frame. The only examples of these embodiments known to the inventor are tractor superstructure suspension systems where at least four suspension points are provided. Two of these suspension points are at the forward end of the vehicle and two are at the rear. No tractor vehicles of which we are aware appear to have the combination forward pivot point and rear suspension with the centering spreader and verticle guide members scheme of this invention.

A tractor comprising a running gear frame section including power train components, front and rear axles (with wheels and tires), and engine and various frame rail sections is provided. This frame is also termed a subframe in this specification. A superstructure including a superstructure frame, the front sheet metal of the tractor, an operator's work platform and a cab which may be built on the work platform to be a part thereof is carried on this subframe section. The superstructure is pivotally mounted to the front of the subframe and is suspended on a coil spring at the rear of the subframe. Through this arrangement the superstructure is capable of vertical movement in a longitudinal plane about the front pivot point.

In order to control sideways or lateral deflection of the superstructure a pair of vertical guide members are fixedly mounted to the subframe. A centering spreader having laterally projecting arms terminating in roller accomodating ends is bolted or otherwise fastened to the rear section of the tractor running gear frame. The centering spreader is located between the vertical guide members such that the rollers carried by the centering spreader simultaneously contact each vertical guide member. This arrangement allows unhampered movement in a vertical plane between the integrated superstructure and the tractor running gear frame.

Downward travel of the cab resulting in compression of the suspension may be limited by elastic snubbers at the bottom of the vertical guide members while upward travel or extension may be limited by inwardly projecting lower portions on the lower ends of the vertical guide members which interact with the rollers affixed to the laterally projecting arms of the centering spreader. Dampening of the suspension travel is accomplished through the use of a shock absorber which may be adjustable to suit the operator.

It is amongst the objects of this invention to provide a tractor vehicle with a cab suspension that will reduce operator fatigue by improving the tractor ride through the use of a cab suspension system where the rear fenders, hood, engine sheet metal and grille all float in unison above the tractor frame.

Furthermore it is an object to provide a suspended cab that is restricted in lateral movement and side blows relative to the tractor frame but is relatively unrestricted in vertical movement over a limited range of travel.

Another object of the invention is that the entire superstructure could be pivoted around the forward pivot point to provide access for servicing the subframe carried components.

Another advantage of this invention is that good operator ride could be accomplished without the need to resort to a suspension seat.

A significant advantage of this invention is that all the operator's controls would float with the cab and the operator.

Also an advantage is that the vibration from the frame, and partially from the clutch housing or rear of the engine, is not transmitted directly into the cab section thus effectively reducing the noise level in the cab.

The above objects and advantages of this invention, as well as others not set forth above, will be apparent through reference to the following drawing figures and the attached explanation presented herein wherein the figures are:

FIG. 1 is a side elevation view of a tractor vehicle incorporating this invention with portions broken away to emphasize the invention;

FIG. 2 is a representation of a rear of a tractor vehicle with portions removed and/or sectioned to shown the invention;

FIG. 3 is a side elevation view of the suspension arrangement;

FIG. 4 is a representation of the front pivoting arrangement; and

FIG. 5 is a view of a tractor vehicle where the superstructure has been pivoted upwardly for rear axle access.

A preferred embodiment answering the objects and advantages as set forth above is presented in the drawing figures in which FIG. 1 presents generally a tractor vehicle 10 which may be considered to have a running gear supporting subframe generally 12 and a superstructure generally 14 which is pivotally mounted to the subframe 12 at pivot point 16.

As shown in the various views the running gear frame or subframe generally 12 is supported by front 20 and rear 22 wheel assemblies (right side only shown), which include typical pneumatic tires and wheels mounted on axles in a conventional manner. An engine supporting frame 24 accomodates a conventional engine 26 as well as a conventional front axle bolster 30. The frame 24 is contiguous and associated with drive train components 32 which typically would include a transmission, rear axle housing, differential housing, brake housing, and hitch control elements 34 as is well known in the art.

In FIG. 2, a centering spreader 36, having laterally projecting arms, 42 and 44, not found in prior art tractor vehicles, is fastened as by fasteners typlified by nut and bolt assembly 40 to an upper component casting of the drive train such as rock shaft housing 46 which may be considered part of the subframe. The centering spreader's laterally projecting arms 42 and 44 locate and retain contact rollers 50 and 52 on the outboard ends of the arms. These rollers may be either metallic, elastomeric or any other composition as may be desirable. The use of elastomeric rollers would serve to allow preloading between the rollers and the vertical guide members 54 and 56. The vertical guide members 54 and 56 are elongated rectangular members bolted, welded or otherwise fastened to the superstructure generally 14 of the vehicle.

Also attached to the surface of the centering spreader 36 is the lower mounting bracket 60 accomodating and grouding one end of a shock absorber 62 (FIGS. 2 and 3). Provisions may also be provided to allow retention of a coil spring 64 to the top side of the centering spreader 36.

Returning to FIG. 1 it can be seen that the superstructure 14 is generally supported on a frame 66 with the forward portion thereof pivoted around pivot point 16. Among the components of the superstructure are the grille 70, the engine hood 72, a cab 74 including a plurality of roof supports 76, 80 and 82, a roof 84, an operator's platform 86 or compartment containing vehicle control equipment such as the steering wheel 90, throttle control 92, instrument panel 94, as well as a seat 96. Fenders such as 100 are provided to partially cover the rear tires.

Superstructure lift handles 102 are provided on the upper portion of the cab 74 to allow the attachment of a hoist that, as will be explained further on, raises the rear of the superstructure and pivots the entire superstructure 14 around pivot point 16.

In FIG. 2 a simplified rear view of the tractor vehicle is provided to show the suspension means suspending the superstructure 14 above the subframe 12. The cab and hitch are among the items left off this view for the sake of clarity. Provided in the figure is the vehicle seat 96 which is supported on pedestal 104 above the floor 106. A relatively narrow structure is provided at the rear part of the operator's platform. This section, generally 110, of the cab provides the mounting location for the left 54 and right 56 vertical guide members that provide alignment guidance that dictates the vertical travel of the superstructure 14 relative to the running gear frame 12. This superstructure is the subfloor extension referred to above. The floor 106 is provided with a cavity 112 to accomodate the coil spring 64 and, in one embodiment, the shock absorber 62 which can be carried in the coil spring. Shock absorber mounting flange 114 is provided to secure the second end of the shock absorber to the floor cavity 112.

It is obvious that the suspension arrangement under the cab allows some arcuate movement of the entire superstructure around pivot point 16. The upward motion of the superstructure is constrained by inwardly bent extensions 116 and 120 of respective left 54 and right 56 vertical guide members which are integral with the superstructure. These extensions limit upward travel when they contract the rollers. Of course the superstructure can move downward from the position shown to compress the spring and shock absorber therefore bumpers or snubbers of elastic material 122 and 124 are provided to snub this action.

Several details of interest are provided in FIGS. 3 and 4. FIG. 3 shows a side elevation view of the suspension system in FIG. 2. The floor 106 and the floor cavity 112 can be seen in the typical relationship with the spring 64, the shock absorber 62 and its lower mounting bracket 60 and mounting flange 114. Rollers such as 52 contact and roll on the vertical guide members. (Vertical guide member 56 is partially broken away to reveal the interior apparatus.)

In FIG. 4 it can be seen how pivot point 16, here represented by axles 126 and 130 are affixed to the bolster 30 which houses the front wheel support 132. The inclusion of a vibration dampening means such as the rubber bushing 128 shown in a broken away view on axle 130 would be desirous to minimize the conduction of noise and vibration into the superstructure. The bushing 138 on axle 126 is illustrative of an alternative non-elastic bushing. One superstructure frame member 66 is identified. Transverse support bar 134 maintains distance between the frame members. Engine enclosure sheet metal 136 would also typically be carried by the superstructure frame members 66. The grille has been left out of this view for the sake of simplicity.

FIG. 6 presents a slightly different shock absorber 140 location. In this embodiment the shock absorber is not mounted inside the spring. In operation the suspension system is identical to that shown in the other figures.

The primary function of building the tractor vehicle as illustrated is to reduce operator fatigue through a more advantageous suspension system. As this tractor is driven the entire superstructure is constantly pivoting around the front pivot point. This would mean that the vehicle operator as well as the steering wheel and all the apparatus of the operator's work station including the vehicle gauges will be undulating in unison while the undercarriage or subframe as well as the hitch and of course its attendant implement will maintain full contact with the ground.

In addition to this advantage the further advantage of this embodiment is shown in FIG. 5 wherein the entire superstructure has been pivoted around the pivot point such that access to various components of the drive train is possible. In order to accomplish this it should be noted that the centering spreader 36 has been unbolted from the fastener 40 such that the spring is still maintained between the centering spreader and the superstructure. With the shock absorber mounted as shown in FIG. 6, i.e. not inside the spring between the centering spreader and the floor cavity, it would be necessary to detach the shock absorber 140 from either the superstructure 14 or the subframe generally 12. In the FIG. 5 embodiment it would be appropriate to lift the superstructure 14 by means provided by the lift handle on the top of the cab 74 identified as item 102.

It should be apparent that there has been provided a suspension cab for use on a tractor chassis that satisfies the objects and advantages as set forth above. While this invention has been described in conjunction with two embodiments thereof it is evident that alternatives and modifications would be apparent to those working in this art in light of this specification. Accordingly this specification is intended to embrace all such alternatives, modifications and variations as found in the spirit and broad scope of the following claims.