Abstract:
A spring movement limiting device that limits lateral shift of a spring in a vehicle suspension along a vehicle axle direction includes a first element and a second element. The first element is coupled to the axle and to the spring. The second element is separate from and engageable with the first element. The second element is fixed at a predetermined position relative to the vehicle axle. Engagement between the first element and the second element limits the first element and spring from movement in the vehicle axle direction.

Description:
RELATED APPLICATION 
     This application claims the benefit of U.S. provisional patent application Ser. No. 60/135,285, filed May 21, 1999. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to an axle seat restraint for a vehicle suspension system, an axle assembly with the axle restraint, and a method of restraining the axle seat during vehicle operation. 
     BACKGROUND OF THE INVENTION 
     FIGS. 1,  2 A and  2 B show a prior art vehicle suspension system in which one or more leaf springs  10  are coupled to an axle  12  with the leaf springs positioned below the axle. In general, configuring the suspension with the leaf springs  10  below the axle  12  provides a lower height suspension, which is desirable in some applications. 
     In this prior art construction, the axle  12  may have an upwardly projecting dowel or pin  14  that is inserted into an aperture of an upper axle retainer  16 . An axle seat  18  is positioned between the leaf springs  10  and the axle  12 . The axle seat  18  bears against the lower surface of the axle  12 . As shown in FIG. 2A, the axle seat  18  may have an aperture  19  for receiving a dowel or pin  21  extending from the upper surface of the uppermost leaf spring of the leaf springs  10  to position the axle seat  18  relative to the leaf springs  10 . The leaf springs  10  may be slidably or otherwise connected directly and/or indirectly (e.g., through shock absorbers as shown or otherwise coupled through other components) to a frame rail  24  of the vehicle. 
     A clamping element  20 , which is generally aligned with the axle seat  18  and the upper axle retainer  16 , may be provided and held in place by a pair of U-bolts  22 , one being positioned on each side of the leaf springs  10 . As a result, the leaf springs  10  and the axle  12  are held in place relative to each other by the combination of the upper axle retainer  16  with the pin  14  received in the aperture thereof, the axle seat  18 , the pin  21 , the clamping element  20  and the U-bolts  22  that secure this assembly together. 
     In other prior art configurations where the axle is positioned below the leaf springs, rather than above the leaf springs as shown in FIGS. 1,  2 A and  2 B, it is possible to weld the axle seat to the top surface of the axle. Due to stress concentrations that occur at the lower surface of the axle, however, welding the axle seat at this location can cause problems. 
     The prior art construction of FIGS. 1,  2 A and  2 B is satisfactory for vehicles operated on smooth surfaces, e.g., highways. After operation under severe conditions, however, such as on washboard roads or during off-road operation, the components of the suspension can wear and/or loosen. As a result, the assembly of the springs, axle seat, axle seat retainer and U-bolts can migrate or shift to some extent in the direction of the axle either inboard toward the frame rail or outboard away from the frame rail, which is undesirable. 
     SUMMARY 
     It would be desirable to provide an axle seat construction that would limit lateral migration or shifting of the leaf spring and the axle seat in the direction of the axle (or “axle direction”) that can occur over the operating life of the vehicle. 
     Accordingly, in one implementation, a spring movement limiting device includes a first element and a second element. The first element is coupled to the axle and to the spring. The second element, which is separate or distinct from the first element, is fixed in place at a predetermined position relative to the vehicle axle. As a result, engagement between the first element and the second element limits movement of the first element along the axle, and thereby also limits movement of the spring along the vehicle axle. 
     The first element may comprise a spring retainer or axle seat, which includes a projecting leg with a slot, and the second element may comprise a fixed-length link with a projection, such as a hook end, which is engageable with the slot. The engagement between the projection and the slot limits movement of the spring retainer element relative to the axle. 
     The second element may be secured at a predetermined position along the direction of the axle, e.g., by being bolted to a brake flange extending from the axle. The second element may comprise a link with at least two apertures and a stem portion projecting from the base that terminates in the projection. The second element may be configured so as not to contact the spring. 
     The brake flange may include a periphery with a plurality of spaced brake flange apertures such that the apertures in the base of the link can be aligned with a corresponding number of brake flange apertures. Although variable, in specific implementations, the base may include two apertures or three apertures. 
     The first element may comprise a spring retainer with a first side with a first projecting leg that includes a first slot, and a second side with a second projecting leg that includes a second slot. This construction facilitates the use of the spring retainer at either side of the vehicle axle as one of the slots is oriented proximate the brake flange for engagement by a link coupled to the brake flange. 
     The axle may include an axle housing and a rotating axle rotatably supported within the axle housing. The axle housing may have a substantially flat surface, and the first element may have a substantially flat mating surface that contacts the flat surface of the axle housing. The first element may abut the axle housing below the axle. Alternatively, the first element may be positioned above the axle and may be separated from the axle by another component. 
     The axle seat may include a spring receiving portion, an engagement portion and an axle coupling portion. The spring receiving portion may be coupleable to a spring of the vehicle. The engagement portion may extend from the spring receiving portion and be slidingly engageable with an axle seat retainer. The axle coupling portion may be coupled to the spring receiving portion and be coupleable to the axle. 
     The spring retainer may include cradle portions extending from the mating surface in the fore and aft directions, respectively. The cradle portions may be engageable with respective fore and aft sides of the axle housing. 
     The axle seat retainer may include a mounting portion that is fixed in place at a predetermined position and an engagement portion attached to the mounting portion. The engagement portion may be slidingly engageable with the axle seat. 
     The first element may include an eyelet or aperture, and the second element may include a hook portion engageable with the eyelet. 
     The present invention is directed to new and unobvious features of this construction alone and in combination with one another, and also to methods related thereto. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation view of a prior art axle seat in a vehicle suspension system with the axle supported above the leaf springs. 
     FIG. 2A is an exploded perspective view of the prior art axle seat and suspension system of FIG. 1 without the axle. 
     FIG. 2B is a perspective view in an assembled state of the prior art axle seat and suspension system of FIG. 1 with the axle shown in dashed lines. 
     FIG. 3 is a perspective view showing one embodiment of an axle seat and axle seat retainer in accordance with the invention positioned against a lower surface of one end of an axle. 
     FIG. 4A is a perspective view of the axle seat of FIG.  3 . 
     FIGS. 4B,  4 C,  4 D and  4 E are respective top, front, side and bottom views of the axle seat of FIG.  4 A. 
     FIG. 4F is a sectional view of the axle seat of FIG. 4A taken along the line  4 F— 4 F of FIG.  4 B. 
     FIGS. 5A and 5B are respective perspective views of axle seats with a single leg according to second and third embodiments. 
     FIGS. 5C and 5D are respective side views of the axle seats of FIG.  5 A. 
     FIG. 6A is a perspective view of the axle seat retainer of FIG.  3 . 
     FIGS. 6B,  6 C and  6 D are respective right side, top and back views, respectively, of the axle seat retainer of FIG.  6 A. 
     FIG. 7A is a perspective view of a second embodiment of the axle seat retainer. 
     FIGS. 7B,  7 C and  7 D are respective right side, top and back views of the axle seat retainer of FIG.  7 A. 
     FIG. 8A is a perspective view of a third embodiment of the axle seat retainer. 
     FIGS. 8B,  8 C and  8 D are respective right side, top and back views of the axle seat retainer of FIG.  8 A. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     According to one embodiment of the invention, and referring generally to FIG. 3, a first element is coupled to a surface of the axle and is also coupled to the spring such that the first element is between the axle and the spring. A second element, which is engageable with the first element, is secured in place so as to be at a fixed position relative to the axle. That is, the second element is prevented from moving in either the inboard or outboard direction along the axle. By engaging the first element with the second element, the first element and the spring are limited in movement in inboard and outboard directions relative to the axle. 
     In the specific implementation of FIG. 3, an axle seat  18 ′ is the first element, and an axle seat retainer  30  is the second element. In the construction of FIG. 3, the axle seat  18 ′ has a body with first and second legs  32 ,  34  projecting respectively toward (outboard) and away (inboard) from the outer end of the axle  12  along the axle. The axle  12  extends in a direction that is transverse to the vehicle frame. The legs  32 ,  34  are each provided with a respective axle seat retainer receiving slot  36 ,  38 , and each can include an axle seat retainer accommodating channel  40  (one being shown in FIG. 3 for leg  34 ). In this construction, the retainer  30  slidably engages the associated slot  36 . The illustrated slots may have other shapes and may extend entirely through the legs as shown or only partially through the legs. Other mechanisms for coupling a retainer to an axle seat may also be used. 
     As illustrated, the leaf springs  10  are positioned beneath the axle  12 , and thus the axle seat  18 ′, which is coupled to the leaf springs  10 , is coupled to the axle  12  from a position below the axle  12 . The axle seat  18 ′ and axle seat retainer  30  may also be configured for applications in which the leaf springs  10  are positioned above the axle  12 . 
     The form of axle seat retainer  30  shown in FIG. 3 comprises a fixed-length link or body with a base  50  that has an arculate periphery and which is fixed to the axle to prevent movement along the axle  12 , such as indicated by an arrow  64 . In the specific implementation of FIG. 3, the base  50  includes a plurality of apertures  52 . The apertures  52  are sized and positioned for alignment with apertures (such as  54 ) in a conventional brake flange  56  that is welded or otherwise included as a part of a brake housing and mounted to the axle  12 . The axle seat retainer  30  is fastened to the brake flange  56 , e.g., by through-bolts  100  and nuts  102  or other suitable fasteners. The axle seat retainer  30  also has a stem or link body portion  60  sized to extend within the channel  40 . Further, the axle seat retainer  30  has a projecting latch or hook portion  62  inserted into the slot  36 . The latch portion  62  in the illustrated embodiment projects in an outward direction from the axle. As a result of this construction, the link body potion  60  is sandwiched or captured between the axle seat  18 ′ and the adjacent surface of the axle  12  when the axle seat  18 ′ and the axle seat retainer  30  are engaged together. 
     In operation, the axle seat retainer  30  cooperates with the axle seat  18 ′ to hold the axle seat  18 ′ and thus the supported springs  10  against sliding either outwardly or inwardly along the axle  12  as indicated by arrow  64 . The axle seat  18 ′ may be detachably coupled to the axle seat retainer  30 . 
     The axle seat  18 ′ and/or the springs  10  may include positioning features to facilitate positioning and aligning these components during assembly. In one specific implementation, the seat  18 ′ has an opening  66  for receiving a dowel or pin (such as the pin  21  in FIG. 2A) projecting upwardly from the springs  10 . The pin  21  is conventional as shown in FIG.  2 A. 
     To minimize parts inventory, the same seat  18 ′ may be used on the opposite end of the axle from that shown in FIG. 3, in which case the latch portion  62  would be inserted into the slot  38 . In the illustrated embodiment, the slots  36 ,  38  are sized slightly greater than the size of latch portion  62  in the direction perpendicular to the base  50  to allow some rotational freedom of the latch portion  60  within the associated slot and to facilitate assembly of the suspension system. 
     The illustrated axle  12  includes an axle housing  42  and a rotating axle portion  44  rotatably supported within the axle housing  42 . In the specific implementation shown in FIG. 3, the axle seat  18 ′ is positioned against the axle housing  42 , and the brake housing and brake flange  56  are also mounted to the axle housing  42 . 
     FIGS. 4A,  4 B,  4 C and  4 D illustrate the seat  18 ′ in greater detail. These figures show the first and second legs  32 ,  34  with the respective axle seat retainer receiving slots  36 ,  38 , the optional pin receiving opening  66  and the axle seat retainer accommodating channel  40 . In addition, as shown, the axle seat  18 ′ includes front and rear legs  80  and  82 , respectively. The front and rear legs  80 ,  82  can include cradle portions  90  and  92  that contact fore and aft surfaces of the axle housing  42 , respectively. In one form, each cradle portion  90 ,  92  includes two upwardly projecting fingers  94  separated by a U-shaped cut-out  96 . 
     As best shown in FIGS. 4C and 4F, a top surface  97  of the axle seat  18 ′ can include an angled or inclined portion that contacts the axle  12  and, more specifically, the axle housing  42  in the illustrated embodiment. The angle of the angled portion is determined based on the desired pinion angle. In a specific implementation, the angled portion is at an angle of about 6° downward, relative to horizontal, from the forward side to the aft side of the seat  18 ′. As best shown in FIG. 4F, a bottom surface of the axle seat  18 ′ may be formed with webs  98  to enhance the structural integrity of the axle seat  18 ′, yet without the added weight of a solid construction. 
     FIGS. 5A and 5B show second and third embodiments, respectively, of the axle seat. These two embodiments are for respective opposite ends of the axle  12 . The axle seat  18 ″ of FIG.  5 A and the axle seat  18 ″′ of FIG. 5B each have a single leg  32 ′ projecting outwardly in an outward direction toward the end of the axle  12  when mounted in place. In other respects, the construction of the axle seats  18 ″ and  18 ″′ is similar to the axle seat  18 ′. FIGS. 5C and 5D show side views of the axle seats  18 ″ and  18 ″′. 
     FIGS. 6A-6D show one form of the axle seat retainer  30  in greater detail. As shown, the illustrated retainer comprises a link with a stem portion  60  that curves from the base  50  to the latch portion  62 . The base  50  is shaped to follow the circumference of the brake flange  56 . The base  50  includes two apertures  52  dimensioned to correspond to two apertures  54  in the brake flange  56 . The apertures  54  in the brake flange  56  used for securing the axle seat retainer  30  may be adjacent or, as shown, non-adjacent (e.g., with one or more unused apertures therebetween). 
     The illustrated latch portion  62  may be slightly wedge-shaped to facilitate engagement with the slots  36 ,  38 . In particular, the outboard side of the latch portion  62  can be tapered by an angle θ, which is shown exaggerated in FIG.  6 B. In one specific implementation, the latch portion is formed with a 3° taper from the stem  60  to the tip of the latch portion  62  on the outboard side of the latch portion  62  that faces the base  50 . Thus, at least a portion of the outboard side surface of the latch portion in this example diverges from the base moving from the stem portion toward the distal end of the latch portion. Similarly, the respective outboard sides of the slots  36 ,  38  may be tapered or inclined (e.g., by 3° ) from the lower surface of the seat  18 ′, i.e., the surface spaced furthest from the axle housing, toward the upper surface of the axle seat, i.e., the surface closest to the axle housing. As a result, engagement between the latch portion  62  and the slots  36 ,  38  occurs at the surface of engagement and the force transmitted through the axle seat retainer  30  is not undesirably concentrated at the tip of the latch portion  62 . 
     FIGS. 7A-7D and  8 A- 8 D show second and third embodiments, respectively, of the axle seat retainer  30 . In the axle seat retainer  30 ′ of the second embodiment and the axle seat retainer  30 ″ of the third embodiment, the stem  60  is split into first and second leg portions  60   a  and  60   b  that join the base  50 . Also, the axle seat retainer  30 ′ and the axle seat retainer  30 ″ each include three apertures  52  for attachment to the brake flange  56 . In the specific implementation shown, the middle of the three apertures  52  is between the first and second portions leg  60   a  and  60   b  of the stem  60 . 
     In the axle seat retainer  30 ′, the latch portion  62  is aligned with the middle of the apertures  52  (FIG.  7 C). In the axle seat retainer  30 ″, the latch portion  62  is offset from the middle of the apertures  52  (FIG.  8 C). The first and second leg portions  60   a  and  60   b  are spaced from the middle aperture to allow access to a nut or through-bolt extending through the middle aperture and between the leg portions  60   a  and  60   b.    
     During assembly, the axle seat retainer  30  is fastened to the brake flange  56 , e.g., with the through-bolts  100  and the nuts  102 , and then the axle seat  18 ′ is placed into contact with the axle  12  with the slot  36  engaged with the latch portion  62  of the axle seat retainer  30 . In addition to the axle seat retainer  30 , the axle seat  18 ′ is secured to the axle with the leaf springs  10 , clamping element  20  and upper axle retainer  16  using U-bolts  22 , as shown in FIGS. 1,  2 A and  2 B, or using other suitable mounting arrangements. 
     The axle seat and axle seat retainer are preferably made of iron, although any other suitable material could be used. 
     Having illustrated and described the principles of our invention with reference to several preferred embodiments, it should be apparent to those of ordinary skill in the art that the invention may be modified in arrangement and detail without departing from such principles. We claim all modifications which fall within the scope and spirit of the following claims.