Abstract:
A vehicle includes a pair of wheel-mounting spindles respectively mounted to a pair of vertically swingable wheel support arms for being steered about respective king pin axes. During assembly of the vehicle on an assembly line, right- and left-hand laser toe gauges are mounted to the spindle shafts in a defined orientation wherein target surfaces of the gauges lie along a respective king pin axis. Length-adjustable tie-rods are coupled to the spindles and adjustable in order that a laser beam emitted from one toe gauge impinges on the target of the other toe gauge when the toe-in is within a prescribed range for resulting in steering and tire wear characteristics. The toe gauges are constructed such that the laser beam direction may be adjusted to calibrate the toe gauge for the particular vehicle being assembled.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a laser based toe-in alignment apparatus for a vehicle having suspended, steerable wheels.  
         BACKGROUND OF THE INVENTION  
         [0002]    The toe of the front wheels of a vehicle is defined as the angular relationship of the principal plane of the front wheel to the vertical plane passing through the longitudinal axis of the vehicle. As viewed from overhead, toe dictates whether or not the tires roll straight down the road. We can refer to toe as the angle of attack for the tires as the vehicle is driven forward. If the front of the tires points towards the centerline of the vehicle, with both tires aiming inboard, this is called toein, because the tires on that axle are aiming inboard. If the front of the tires is aiming in an outboard direction, away from the centerline of the vehicle, this is referred to as toe-out. A slight amount of toe-in is normally desirable for good handling and tire wear characteristics.  
           [0003]    The toe-in of the steerable front wheels of a vehicle has to be properly set since, if otherwise, poor steering and/or high rates of tire wear will occur. Generally, commercially available tools use a vehicle&#39;s installed wheels to assess or establish wheel toe-in condition, and lasers and/or mechanical indicating devices are typically employed in these tools and processes. There are laser and mechanical devices and methods that use equipment attached across the vehicles steering components to indicate the state of toe-in. The use of a cross-vehicle mechanical apparatus requires time and care to establish and attachment or alignment to both wheels or rims to allow for toe-in setting and are not easily adapted to the environment of a manufacturing assembly line. One known alignment system required two operators to lift, locate and secure the device across the front of the vehicle. Indicating arms were located on each axle spindle and the tie rod ends were adjusted to bring each of the indicating arms into alignment with target lines on the cross-vehicle device.  
           [0004]    U.S. Pat. No. 3,782,831 discloses a toe-in setting assembly including a pair of light-emitting and receiving devices respectively coupled to opposite steerable wheels, the devices being electrically coupled to a control console including display meters for indicating the toe-in angle in accordance with signals sent by the devices. This device requires significant care in its leveling and alignment with each wheel rim before measurements or adjustments can be accurately effected. The set up time for these types of devices are relatively long and significant time is required for an operator to master the technique of properly using these devices. U.S. Pat. No. 4,115,926 discloses a toe-in setting system which is said to overcome the need to level separate devices coupled to wheels, the separate devices of the patent each producing a beam of light and each including a lined target screen for receiving the light beam of the other device.  
           [0005]    The prior art also includes a cross-vehicle mechanical apparatus that fastens to each king bolt and uses devices attached to each axle spindle to indicate toe-in relative to a target line of the apparatus. This equipment is time consuming to attach and has excessive setting variability due to parallax between the indicating elements, operator uncertainty with respect to target acquisition and also through the number of interfaces in the process. The weight of this cross-vehicle device needs to be minimized to allow for repeated lifting by assembly operators. The light weight requirement, however, creates a device that is not robust enough to maintain its shape through repeated use.  
         SUMMARY OF THE INVENTION  
         [0006]    According to the present invention, there is provided an improved toe-in setting arrangement which includes a pair of companion toe gauges mounted to the opposite steerable wheels or wheel-mounting spindles of the vehicle.  
           [0007]    An object of the invention is to provide a toe-in setting arrangement which includes a pair of companion toe gauges that are each of a simple, reliable design, with the procedure for setting the toe-in with the devices being one that can be quickly mastered by an assembly line worker.  
           [0008]    A more specific object of the invention is to provide a toe-in setting arrangement as set forth in the immediately preceding object wherein the toe gauges are particularly adapted for being used in a vehicle assembly line prior to the wheels being mounted on the spindles.  
           [0009]    Yet another object of the invention is to provide a toe-in setting arrangement, as defined in the foregoing objects, wherein the mounting of each companion toe gauge to the vehicle requires a minimum number of interfaces with the vehicle.  
           [0010]    The objects of the invention are achieved by a toe-in setting arrangement including two opposite hand companion toe gauges, with each device being located on an opposite axle spindle and having a target and a laser light assembly aligned with the longitudinal axis of its associated king pin. Each target has a target face that is located along the axis of the associated king pin. The laser in the device produces a reference beam which is calibrated to produce the required toe-in angle. As the tie rod end is adjusted, the device&#39;s laser beam locates the target face of the companion toe-in device. Since the target face is along the king pin axis and the axle spindle rotates about the king pin, each device can be rotated independently without displacing the target provided to the companion toe-in setting device. Thus, the king pins jointly serve as the datum for the toe-in angle.  
           [0011]    These and other objects of the invention will become apparent from a reading of the ensuing description together with the appended drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a left front perspective view of a vehicle with which the present invention has utility.  
         [0013]    [0013]FIG. 2 is a front elevational view showing a partially assembled vehicle in a condition where its toe-in is being checked using the toe-in setting arrangement of the present invention.  
         [0014]    [0014]FIG. 3 is a front elevational view of the rack and pinion steering assembly that is only partially shown in FIG. 2.  
         [0015]    [0015]FIG. 4 is a left rear perspective view showing a portion of the left-hand wheel support structure and steering arrangement together with the left-hand toe gauge.  
         [0016]    [0016]FIG. 5 is a right front perspective view showing the lower portion of the mounting of the left-hand spindle to the king pin, and the left-hand toe gauge.  
         [0017]    [0017]FIG. 6 is a right front perspective view of the left-hand toe gauge with parts removed showing an exploded view of the laser light assembly and the eccentric rings for adjusting the direction of the laser light beam. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]    Preliminarily, it is noted that all references made to “right-hand”, “left-hand”, “right” or “left” are all made relative to a position behind the vehicle and looking in the direction of forward travel.  
         [0019]    Referring now to FIG. 1, there is shown a utility vehicle  10 , including a chassis or frame  12  supported on two pairs of driven rear ground wheels  14  and  16 , respectively, and a pair of steerable front wheels  18 . Mounted to the frame  12  in a location over the rear pairs of wheels  14  and  16  is a cargo bed  20 . Driver and passenger seats  22  and  24 , respectively, are located just forward of the cargo bed  22  in side-by-side relationship to each other. A steering wheel  26  is located in front of the driver seat  24  for controlling the steering of the front wheels  20 , in a more-or-less conventional manner described below in further detail. In a manner described more fully below, the front wheels  18  are suspended from the frame  12  for swinging vertically and this movement is dampened by a spring-over-shock absorber strut arrangement  27  mounted between each wheel support arm and the frame  12 .  
         [0020]    Referring now to FIG. 2 there is shown right- and left-hand wheel support arms  28  and  30 , respectively, right- and left-hand spindles  32  and  34 , respectively, portions of right- and left-hand tie rods  36  and  38 , respectively, and right- and left-hand laser-based toe gauges  40  and  42 , respectively.  
         [0021]    The right-hand wheel support arm  28  has an outer end defined by an upwardly and inwardly inclined, cylindrical housing  44  to which is joined outer ends of upper and lower formed tubes  46  and  48 , respectively, having fore-and-aft displaced inner ends defined by fore-and-aft extending cylindrical receptacles  50  and  52 , in which are received bushings  54  and  56 , including elastomeric members. The receptacles  50  and  52  are located between, and coupled to, sets of mounting lugs provided on the support frame  12  by mounting bolts (not shown), the bolts cooperating with the bushings  54  and  56  such that the support arm  28  may swing vertically. Mounted between the frame  12  and the arm  28  so as to retain the latter in a desired location for the toe-in setting operation is a rigid strap  58 .  
         [0022]    The spindle  32  is defined by a spindle shaft  60  having a threaded outer end and which extends substantially horizontal for receiving a wheel and wheel mounting nut (not shown) during the assembly process. Provided for mounting the spindle shaft  60  for swiveling about a king pin axis is an integral yoke including upper and lower arms respectively disposed at upper and lower ends of the housing  44  and coupled for rotating within a cylindrical king pin or bushing (not visible) located in the housing  44  by a king bolt  62  having a threaded lower end receiving a nut  64 . Referring now also to FIG. 3, it can be seen that the right-hand tie rod  36  is pivotally attached to a steering arm  66  fixed to and projecting rearwardly from the upper yoke of the spindle  32  by a depending stem of a ball connector  68  having its ball end received in a complementary shaped socket formed in an outer end of a tie rod end  70 . The tie rod end  70  has a threaded bore receiving a threaded end of an inner section  72  of the tie rod  36 , the tie rod end  70  including an integral nut  74  adapted for being engaged with a open end of an adjusting tool. The tie rod  36  is universally coupled, as at a ball-and-socket joint  76 , to a right end of a steering output member  78  having a gear tooth rack formed along its length and engaged with a pinion gear carried at the bottom of a steering shaft  80 .  
         [0023]    Similarly, the left-hand wheel support arm  30  includes an outer end defined by an upwardly and inwardly inclined, cylindrical housing  82  to which is joined outer ends of upper and lower formed tubes  84  and  86 , respectively, having inner ends defined by cylindrical receptacles  88  and  90 , respectively, which are displaced fore-and-aft from each other and contain bushings  92  and  94 , which include elastomeric bodies. The receptacles  88  and  90  are respectively located between pairs of mounting lugs (not shown) joined to the frame  12  and respective mounting bolts (not shown) extend through the lugs and bushings so as to mount the arm  30  to the frame  12  for vertical swinging movement. Mounted between the frame  12  and the arm  30 , in lieu of the coil-over-shock absorber strut arrangement  27 , which is assembled later in the process, is a rigid strap  96  which serves as a dummy strut to hold the arm  30  at a desired position for the toe-in setting operation. The length of this strut is predetermined to be that which corresponds to that of the strut  27  when the vehicle  10  is parked without a rider or any load, it being noted that an increase in the length of the strap  96  will increase toe-in while a decrease of the length of the strap will increase toe-out, and when weight is added to the machine, toe-in will increase while removal of weight will result in the opposite toe movement.  
         [0024]    The left-hand spindle  34  is defined by a spindle shaft  98  having a threaded outer end and which extends substantially horizontally for receiving the left-hand wheel  18  and retaining nut (not shown), which are mounted later in the assembly process. Provided for mounting the spindle shaft  98  for swiveling about a king pin axis is an integral yoke including upper and lower arms respectively disposed at upper and lower ends of the housing  82  and coupled for rotating within a cylindrical king pin or bushing (not visible) located in the housing  82  by a king bolt  100  having a lower end receiving a nut  102 . Referring also to FIG. 4, it can be seen that the left-hand tie-rod  38  is pivotally attached to a steering arm  104  by a depending stem of a ball connector  106  having its ball end (not visible) located within a complementary ball socket provided at the outer end of a tie rod end  108 . The tie rod end  108  has a threaded bore receiving a threaded end of an inner section  110  of the tie rod  38 , the tie rod end  108  including an integral nut  112  adapted for being engaged with a open end of an adjusting tool. The tie rod  38  is universally coupled, as at a ball-and-socket joint  114 , to a left end of the steering output member  78 .  
         [0025]    As can be seen in FIG. 2, the right- and left-hand toe gauges  40  and  42  are respectively mounted to the spindle shafts  60  and  98  of the spindles  32  and  34 . The toe gauges  40  and  42  are of an identical construction, and for the sake of simplicity, the components of each will be identified with the same reference numerals. Thus, with reference also to FIGS. 3 and 4, it can be seen that each toe gauge  40  and  42  includes an elongate body  120  which, as considered in FIG. 2, is rectangular in side view. Received in a circular opening in an upper location of, and fixed to, the body  120  is a cylindrical spindle receptacle  122 , with the receptacles  122  of the devices  40  and  42  respectively being received on spindle shafts  60  and  62 . A knurled thumb wheel  124  is joined to a threaded shaft (not visible) and is screwed into an axially threaded bore provided in each of the shafts  60  and  62 , and when tightened against the receptacles  122 , as illustrated in FIG. 4, holds the toe gauges  40  and  42  securely against a bearing shoulder (not visible) formed on the each of the shafts  60  and  62 . As can best be seen in FIG. 5, an inverted L-shaped alignment tab  126  is fixed at a location approximately half-way between top and bottom ends of, and on an inner surface of, the body  120 , the tab  126  having a vertical leg  128  and an inwardly projecting horizontal leg  130 , the latter having a notch or recess  132  at its inner end which receives the lower end of the adjacent king bolt  62  or  100  when the body  120  is correctly positioned. Fixed to an inner surface of the vertical leg  128  of the alignment tab  126  is a target  134  having an inwardly directed target face  136  located along the axis of the associated king pin bolt  62  or  100 . Thus, the target face  136  remains along the king bolt axis no matter what angular position the spindle  34  occupies. Located on the inner surface of the body  120  directly below the target face  136  is a hollow conical housing  138  that contains a laser light assembly  140 .  
         [0026]    Referring now also to FIG. 6, it can be seen that the laser light assembly  140  includes a laser unit  142  fixed to a cylindrical grommet  144  that is in turn coupled to a ball segment  146  located within a complementary socket of a bearing housing  148 , the ball segment and housing forming a swivel bearing which permits the direction of the light beam emitted by the laser unit  142  to be adjusted. This adjustment is accomplished by inner and outer adjustment rings  150  and  152 , respectively, having eccentric inner bores  154  and  156 . The body  120  is provided with a cylindrical opening  158  which leads into the conical housing  138  on the opposite side of the body. The cylindrical grommet  144  of the laser assembly  140  fits snugly within the eccentric bore  154  of the inner adjustment ring  150  and the inner adjustment ring  150  in turn fits snugly within the eccentric bore  156  of the outer adjustment ring  152 . The inner adjustment ring  150  is provided with a pair of diametrically opposite pin holes or receptacles  160  for receiving pins of a first adjustment tool (not shown) that is in the form of a ring. Similarly, the outer adjustment ring  152  is provided with diametrically opposite pin holes  162  for receiving pins of a second adjustment tool (not shown) having an inside diameter large enough to loosely fit over the outer diameter of the first tool. Thus, by using the adjustment tools, the adjustment rings  150  and  152  may be rotated relative to each other until the laser unit  142  is aimed to project a light beam in a desired direction, which is determined in a manner described below. Once the laser unit  142  is properly oriented, the adjustment rings  150  and  152  are locked in their adjusted positions by tightening a set of three locking screws (not shown) which are respectively located in a set of three holes  163  provided in a clamping ring  164  and threaded into a set of three threaded holes  166 , located in a shoulder  168  surrounding the entrance to the bore  154 . The clamping ring is dimensioned to partially overlap the inner end of the outer adjustment ring  152  with the clamping force exerted on the ring  152  acting to cause it to expand radially outward sufficient to effecting a gripping action between the interfaces of the bore  154  and the outer ring  152 , the bore  156  of the outer adjustment ring and the outer surface of the inner adjustment ring  150  and the inner bore  154  of the inner ring  150  and the cylindrical surface of the grommet  144 .  
         [0027]    As can be seen in FIG. 4, the outer end of the bore containing the laser light assembly  140 , adjusting rings  150  and  152  and the clamping ring  164  is closed by a cover plate  170 , the top of which is held in place by a lip formed on the bottom of a clip  172  secured to the body  120  by a fastener  174 . A generally C-shaped handle  176  is secured to the outer surface of the body  120  by screws (not shown) located in top and bottom ends of the handle, with the bottom screw clamping the bottom end of the handle against the lower part of the plate  170 . A generally C-shaped hanger bracket  178  is fixed to the top of the body  120  and adapted for being clipped to a flexible tether (not shown) secured to an overhead support of the assembly line so as to suspend the gauge  42  during the time between operations on different vehicles.  
         [0028]    As shown in FIGS. 4 and 5, power is connected to the laser unit  142  by way of a flexible power line  180  extending from a power source (not shown) and having a coupler  182  containing a pair of leads (not shown) ending in a pair of prongs engaged with mating receptacles formed at the ends of leads of a coupler (not shown) projecting through the inner surface of the gauge body  120  from a passage (not shown) that leads to a wire channel  184  (FIG. 6) formed in the outer surface of the body  120 . These leads go to a switch  186  located beneath the spindle shaft receptacle  86  and including a normally open switch element  188  that projects through an opening provided in the receptacle  86  so that it is moved to a closed position only when the toe gauge  42  is mounted on the spindle shaft in a proper position for gauging operation. This ensures that the laser light  142  is not unintentionally illuminated. A pair of lead sections  190  and  192  extend down through the lead channel  184  from the switch  186  and are coupled to lead sections  190 ′ and  192 ′ connected to the laser unit  142 . Specifically, the lead section  190  includes a coupler section  194  engaged with a coupler section  194 ′ of the lead section  190 ′; and the lead section  192  includes a coupler section  196  engaged with a coupler section  196 ′ of the lead section  192 ′. These separable coupler sections may be selectively uncoupled, as shown in FIG. 6, so that the lead sections  190 ′ and  192 ′ may be coupled so as to power the laser unit  142  from an alternate location, such as at a test bed when the laser light assembly  140  is being calibrated, i.e., adjusted for emitting light in a desired direction for impinging the target surface  136  of a companion toe gauge. An elongate cover element  188  (FIG. 4) is releasably retained over the lead channel  184 .  
         [0029]    Referring to FIG. 2, it can be seen that when the toe-in is properly set on both sides of the vehicle, in a manner described below, the laser light from the right-hand toe gauge  40  will emit a beam  200  which impinges on the target face  136  of the left-hand toe gauge  42 , while the left-hand gauge  42  will emit a beam  202  which impinges on the target face  136  of the right-hand gauge  40 .  
       Operation  
       [0030]    The first step in preparing for setting the toe-in on vehicles  10  being assembled on an assembly line is to calibrate the companion set of toe gauges  40  and  42 , respectively. This is done by taking the gauges  40  and  42  to a previously prepared test bed which replicates wheel mounting aspects of the particular vehicle being gauged. The following steps are then performed relative to each gauge:  
         [0031]    1. The cover plate  170  and cover element  198  are removed from the gauge body  120  to gain access to the adjustment rings  150  and  152 , and to the wiring in the lead channel  184  by removing the fastener  174  from the retaining clip  172  and the mounting screw of the handle  176 .  
         [0032]    2. Next, the coupler sections  194  and  194 ′ of the lead sections  190  and  190 ′, and the coupler sections  196  and  196 ′ of the lead sections  192  and  192  are disconnected so that the laser unit  142  is disconnected from the switch  186 .  
         [0033]    3. The three set screws holding the clamping ring  164  are loosened so as to free the inner and outer adjustment rings  150  and  152 .  
         [0034]    4. The shaft receptacles  122  of the toe gauges  40  and  42  are then mounted on the respective shafts of the test bed that replicate the right- and left-hand spindle shafts of the vehicle to be gauged, with the thumb wheels  124  being applied to the threaded shaft ends to hold the gauges in place.  
         [0035]    5. Then, for setting the beam alignment of the right-hand gauge  42 , two concentric ring-like adjustment tools are then slipped over the leads going to the laser unit  142 , with respective pins of the inner tool being placed into the pin holes or receptacles  160  of the inner adjustment ring  150  and with the pins of the outer tool being placed into the holes or receptacles  162  of the outer adjustment ring  152 .  
         [0036]    6. The lead coupler sections  194 ′ and  196 ′ of the lead sections  190 ′ and  192 ′ going to the laser unit  142  are coupled to a test bed power source.  
         [0037]    7. Next, the ring-like tools are swiveled relative to each other so as to cause corresponding swiveling of the adjustment rings  150  and  152  so as to cause the light beam emitted by the laser unit  142  to be directed onto the target face  136  of the left-hand toe gauge  42 .  
         [0038]    8. The three locking screws of the clamping ring  164  are then tightened to retain the adjustment rings  150  and  152  in their adjusted positions.  
         [0039]    9. The toe gauge  40  is then removed from the shaft, the lead portions going to the laser unit  142  are disconnected from the test bed power source, and the two ring-like tools are removed.  
         [0040]    10. The lead portions  190 ′ and  192 ′ going to the laser unit  142  are then reconnected with the lead portions  190  and  192  going to the switch  186 , the cover plate  170  and cover element  198  are re-installed and the right-hand toe gauge  40  is once again mounted on the axle of the appropriate spindle shaft of the test bed.  
         [0041]    11. The same adjustment process may be applied for adjusting the position of the laser beam of the left-hand toe gauge  42  either concurrently with, or subsequently to, the adjustment of the right-hand toe gauge  40 , the adjustment motion of either not affecting the other.  
         [0042]    Once the right- and left-hand gauges  40  and  42  are calibrated, they are removed front the test bed and their hanger brackets  178  are coupled to respective tethers at the assembly line location where the gauges are to be used. One of the gauges  40  and  42  is plugged into the power source at the assembly line by establishing the connection between the coupler  182  of the power line  180  with the coupler at the inner surface of the gauge body  120 .  
         [0043]    Once a partially assembled vehicle  10  is moved into place, the toe gauges are mounted on the spindle shafts  60  and  90 , with the recesses  132  of the respective alignment tabs  126  having the lower ends of the king bolts  62  and  100 . The vehicle steering shaft  80  is rotated to a position corresponding to straight ahead steering of the vehicle and fixed in place.  
         [0044]    Assuming the right-hand toe gauge  40  to be the one coupled to power, the laser light unit  142  will become energized only after the shaft receptacle is mounted in place on the spindle shaft  60 , it being noted that during this mounting the normally open switch  186  is closed to complete the circuit to the laser light unit  142 . The operator will observe whether or not the emitted laser light beam is impinging on the target face  136  of the left-hand gauge  42 . If it is does, the toe-in is correct and corresponds to that of the “standard” of the test bed set up. If not, the operator will engage the tie-rod end nut  74  with a wrench or tool and turn it in the appropriate direction for causing the right-hand spindle to be adjusted so as to cause the laser beam emitted from the right-hand toe gauge  40  to impinge on the target face  136  of the companion gauge  42 , this impingement indicating that the correct toe-in has been set. The procedure will then be duplicated for setting the toe-in of the left-hand side of the vehicle, with the operator manipulating the tie-rod end nut  112  if necessary to cause the position of the left-hand spindle to be adjusted such that the laser beam emitted by the left-hand toe gauge  42  impinges the target face  136  of the right-hand toe gauge  40 .  
         [0045]    Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.