Patent Application
20070138754
1. Field of the Invention
This invention relates to steer axle assemblies and, in particular, to a heavy duty steer axle assembly with a kingpin and live spindle.
2. Discussion of Related Art
Forged beam axles are used on a variety of vehicles, including large vehicles such as light trucks and commercial trucks. These axles endure high loads which are transmitted to the axle through the wheel. In a conventional steer axle assembly, a steering knuckle supports the wheel and connects the wheel to the axle beam. The steering knuckle is attached to the axle beam with a kingpin. The kingpin is disposed in a bore on the end of the axle beam and may be kept stationary relative to the axle beam while the steering knuckle rotates about the kingpin in response to action of the steering linkage. A non-rotatable spindle that is integral to the steering knuckle, termed a “dead” spindle, extends outward from the steering knuckle. A wheel hub, including a wheel mounting flange, is supported for rotation on the spindle by a bearing assembly. A wheel and tire assembly may then be attached to the wheel mounting flange.
In conventional steer axle assemblies for heavy vehicles a forged knuckle is required in connection with the spindle because the dead spindle must withstand high bending loads. Forged knuckles are difficult and expensive to manufacture. Furthermore, conventional steer axle assemblies require removal of the wheel hub and wheel bearings in order to remove and service a brake rotor. Further, in order to enable wheel flanges with varying offsets to be used, a unique wheel assembly for each offset is required.
The inventors herein have recognized a need for a steer axle assembly that will minimize and/or eliminate one or more of the above-identified deficiencies.
The present invention provides a steer axle assembly for a vehicle with a live spindle.
A steer axle assembly in accordance with the present invention includes an axle beam extending transversely across the vehicle. The axle beam has a kingpin bore at a first end. The steer axle assembly further includes a kingpin disposed in the kingpin bore, a knuckle mounted on the kingpin and rotatable relative to the axle beam, and a spindle hub configured to mount a wheel of the vehicle. A bearing assembly is disposed between the knuckle and the spindle hub.
A steer axle assembly in accordance with the present invention is a significant improvement over conventional steer axle assemblies for heavy duty vehicles. The use of a live spindle on a heavy duty vehicle enables the use of a cast knuckle, rather than forged knuckle. A cast knuckle is easier and less expensive to manufacture than a forged knuckle. Use of a cast knuckle is enabled because the bending loads of the vehicle are not reacted by a dead spindle, but by the bearing bore of the knuckle and the fastening bolts located further out radially from the wheel centerline. Further, the use of a live spindle allows for removal and service of the brake rotor without removal or readjustment of the wheel bearings. Further, the use of a live spindle allows for an external wheel flange that can be easily replaced with other flanges of varying offset, without requiring a new wheel hub assembly to accommodate the varying offsets.
These and other advantages of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example.
Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views,
Axle beam 12 is provided to support a vehicle (not shown) on wheels (not shown) disposed proximate either end of beam 12. Beam 12 extends transversely across the vehicle. Beam 12 may be made be from steel and may be forged or fabricated. Axle beam 12 may be a conventional forged I-beam or a tubular beam, for example, and may be straight of may define a gooseneck at either end. Each end (only one of which is shown in
Kingpin 14 is provided to couple knuckle 16 to beam 12. Kingpin 14 may be made from steel or other conventional metals or metal alloys. Kingpin 14 is disposed within kingpin bore 24 at one end of axle beam 12. Kingpin 14 has a first portion rotatably supported by bearings 26 within bore 24 of beam 12 and a second portion fixedly coupled within a bore 38 of knuckle 16. Alternatively, kingpin 14 may be fixedly coupled within bore 24 of beam 12 and knuckle 16 may be rotatably supported on kingpin 14. Kingpin 14 may be fixedly coupled within bore 38 of knuckle 16 in a conventional manner through the use of one or more drawkeys. Kingpin 14 has a longitudinal body 40 disposed about an axis 42. A first axial end of kingpin 14 defines an end flange 44 that extends radially outwardly from body 40 and is disposed against knuckle 16. A second axial end of kingpin 14 defines a partially threaded shank 46 that extends outwardly from bore 24 of beam 12. A washer 48 and a nut 50 may be disposed about shank 46 in a conventional manner to retain kingpin 14 within bores 24, 38. Kingpin 14 and washer 48 also together form a shoulder against which bearing cone 30 is supported. An opposed shoulder, against which bearing cone 28 is supported, is formed by a stepped diameter in body 40 of kingpin 14.
Knuckle 16 is provided to allow steering of the wheels mounted at either end of the steer axle. In accordance with the present invention, knuckle 16 may be cast rather than forged because the use of a live spindle reduces loads transferred through the knuckle. Knuckle 16 is mounted on kingpin 14 and is rotatable relative to axle beam 12. Referring to
Body 52 provides structural support for the other components of knuckle 14 and defines a second boss 58 for receipt of kingpin 14. Boss 58 is in the form of a unitary sleeve and includes bore 38 which is configured to receive kingpin 14. The angle of axle bore 24 and knuckle bore 38 are such to position kingpin 14 generally vertically, preferably at some angle inboard from a vertical position to assist steering. Body 52 may define a plurality of mounting pads 60, 62, 64 for brake components and steering member 54.
Steering member 54 is provided to couple knuckle 16 to the steering mechanism of the vehicle. Steering member is a unitary (i.e., one piece) member that defines a steering arm 66 and a tie rod arm 68 that supports a tie rod (not shown) extending generally parallel to beam 12. Member 54 may be bolted onto body 52 or otherwise conventionally fastened to body 52. Alternatively, member 54 could be made unitary with body 52.
Knuckle flange 56 is provided to support spindle hub 18 and bearing assembly 20. Flange 56 defines a central recess 70 that extends in an outboard direction and is configured to receive spindle hub 18 and bearing assembly 20. Flange 56 also defines a plurality of bores 72 for a purpose described hereinbelow.
Spindle hub 18 is provided to mount a wheel (not shown) of a vehicle. Hub 18 includes body 74 and a support flange 76 disposed at an outboard end of body 74. Body 74 is tubular and is configured to support bearing assembly 20. In the embodiment illustrated in
Support flange 76 is provided to support a brake rotor 84 and a wheel flange 86 to which a vehicle wheel (not shown) is mounted. Referring to
Bearing assembly 20 is provided to allow relative rotation between spindle hub 18 and knuckle 16. Bearing assembly 20 is pressed onto spindle hub 18. Bearing assembly 20 includes bearing cones 102, 104 with cones 102, 104 adjacent to one another. Cones 102, 104 form inner bearing races and provide a bearing surface for spindle hub 18. Bearing assembly 20 further includes a unitary bearing cup 106 disposed radially outwardly of both cones 102, 104 and forming a pair of outer bearing races. An inboard end of cup 106 is sized so as to be received within outboard central recess 70 of knuckle 16. Cup 106 also defines a radially extending flange 108. Flange 108 defines a plurality of bores 110 configured to align with corresponding bores 72 in knuckle flange 56. Bores 110 and 72 are configured to receive fasteners 96 such as bolds, pins or screws used to fasten bearing assembly 20 to knuckle 16. Fasteners 96 are inserted on an outboard axial side of cup flange 108 and are received in knuckle flange 56.
A steer axle assembly 10 in accordance with the present invention represents an improvement as compared to conventional steer axle assemblies. The use of a live spindle 18 on a heavy duty vehicle with an axle 12 and kingpin 14 enables the use of a cast knuckle 16, rather than forged knuckle, that is easier and less expensive to manufacture. Further, the use of a live spindle 18 allows for removal and service of the vehicle's brake rotor 80 without removal or readjustment of the wheel bearings 20. Finally, the use of a live spindle 18 allows for an external wheel flange 82 that can be easily replaced with different flanges of varying offset, without requiring a new wheel hub assembly to accommodate the varying offsets.
While the invention has been shown and described with reference to one or more particular embodiments thereof, it will be understood by those of skill in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
