CA2485543A1 - Wheel alignment gauge - Google Patents

Abstract

The present invention is a gauge for checking a vehicle's wheel alignment for toe, camber, and caster. The gauge is used with the vehicle on the ground and its wheels on.
The gauge comprises equal length extension rods, with magnets at each end, at least three of which are inserted through each wheel's vent holes or spokes. Their inboard ends magnetically attach to the disc brake rotor's surface behind the wheel, and they extend perpendicularly therefrom.
Sheet steel plates rest on the ground beyond the bodywork and magnetically attach to the rod's outboard ends. Alignment arms magnetically attach to these plates. The arms extend from the plates and have lasers at their ends. The lasers aim perpendicularly across the vehicle at each other. Each arm has an abutment arm which contact's the leading edge of each wheel (or rotors, when the wheels are removed). Targets on each laser have center holes and a printed grid. The laser dots, if not on center, provide a first measurement, and the distance between the arms the second. The number obtained by dividing the first by the second, gives the SINE of the wheel's angle. Published SINE Tables (or a calculator), gives the wheel's angle. The gauge can be quickly mounted both vertically and horizontally for camber or toe measurements respectively.
The gauge is attached to the rotor when the wheels are off, to direct alignment adjustments.

Description

FIELD OF THE INVENTION
A low-cost gauge or jig for checking the wheel alignment of cars and other vehicles. The gauge uses the disc brake rotor as the reference plane for alignment.
BACKGROUND OF THE INVENTION
Wheel alignment saves fuel, provides safer steering and braking, and reduces tire wear. There is a need for a reasonably accurate and low priced gauge that small shops and gas/service stations can quickly use to check wheel alignment as a routine service for customers, and to guide wheel alignment after replacing shock absorbers, ball joints, and steering-rod-ends.
SUMMARY OF THE INVENTION
The present invention is a gauge that uses one or more double-ended magnetic extension rods of equal length that pass through the vent or spoke openings in the vehicle's wheels (front and/or rear) and magnetically attach to and extend perpendicularly from, the disc brake rotor surface. Preferably three extension rods are used. A flat metal plate (steel) is attached to the magnetic outer ends of these extension rods to become the planar reference surface clear of the vehicle's bodywork, from which wheel alignment is determined. Alignment arms with lasers are magnetically attached to each plate. The arms have perpendicular abutment arms that contact the leading edge of each wheel. The alignment arms can be attached horizontally to project their laser beams across the the front of the vehicle onto a target sheet where the laser dot indicates "toe"; or vertically, to project the laser beams across the top of the vehicle's hood to check for "camber". When the steering wheel is turned in increments, the lasers dot's sequential locations on the target trace an arc (connect the dots on the target) the arc depicting a wheel's caster setting.
A detailed explanation of the complex determination of caster measurement is given at:
http://www.hunter.com/pub/undercar/2573T/steer.htm.
If wheel alignment is required, the gauges are removed, the vehicle is jacked up on its suspension arms (not on the vehicle's frame) just enough to allow removal of the wheels. In this way the suspension remains weight loaded, just as it is when on the ground.
The gauges are then remounted to the exposed brake rotors, the abutment transferred to contact the rotor's circumference and corrective adjustment carried out unfit the laser dots on the targets indicate correct alignment.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 A perspective view of a disc brake rotor and plate supported thereon using equal length, double ended magnetic extension rods, and with laser lamps on the metal disc beaming to targets at the front, rear, below, or above the laser;
Figure 2 a side view of a wheel showing the extension rods inserted between spokes;
Figure 3 a front view showing the wheel, brake rotor, extension rods, metal plate, lasers, and targets above and below the laser;
Figure 4 a perspective view of an magnet-ended extension rod and showing an offset adaptor for the inboard end for reaching discs whose diameter smaller than the wheel's vent hole circular pattern;
Figure 5 a top and/or front view of the tool installed on two wheels showing the laser beams being non-coincident indicating an (exaggerated) degree of toe-in for a top view, and, of positive camber in a front view;
Figure 6 shows the same view with the wheels removed and a clamp used to hold one alignment arm to the rotor;
Figure 7 shows a side view where the alignment arm is held to the extension rods using a clamping arrangement and an abutment rod contacts the front of the tire;
Figure 8 the same embodiment with the wheel removed and a rear abutment rod contacting the rear of the rotor;
Figure 9 shows a top view of the same embodiment;
Figure 10 shows an embodiment where the plate is resting on the ground and the alignment arm is magnetically attached to the plate, a support rod and level allow each side to be positioned identically, and a locating pin in the alignment arm engages a hole in the plate;
Figure 11 shows the same embodiment used vertically to test wheel camber and showing the abutment rods contacting the top center of the tire, and showing on one gauge, how a mirror may be used to project the laser beam towards the mechanic adjusting a wheel's alignment;
Figure 12 shows a front view of the same embodiment;
Figure 13 shows an embodiment with two linear bearings added;
Figure 14 shows the same embodiment with a single double motion linear bearing;
Figure 15 shows an embodiment with a pivoting bearing added;
Figure 16 shows the measurements needed to calculate the sine of the degree of the wheel's angle;
Figure 17 shows a simple single rotatable extension rod embodiment with a magnet on one and and a laser on the other which attaches to an exposed brake rotor;
Figure 18 shows the same embodiment where the rod passes through an opening in the wheel to reach the brake rotor;
Figure 19 shows an end view of the two alignment arms and how the laser lamps may be offset on the arms so that the beams are clearly visible on the target arm and not obstructed by the laser lamp body or its lens;
Figure 20 shows and end view of how a magnetically attached carpenter's inclinometer or angle indicator may be used in conjunction with part of the present invention to determine wheel camber angle.
Figure 21 diagrammatically shows how a common laser distance measuring unit with calculator may be incorporated in one alignment arm to quickly measure the distance between the two alignment arms and compute the wheel angle for this distance and the distance of misalignment of the laser dot on the target with the opposing laser lens at the target's center;
Figure 22 shows how the laser may be rotatably mounted on the alignment arm with index marks to indicate wheel TOE angle;
Figure 22 shows how an end portion of the alignment arm may be made rotatable also with index marks to indicate wheel CAMBER angle.
DETAILED DESCRIPTION OF THE INV ENTION
Vehicle wheels are factory aligned (actually misaligned) in the forward plane to have a specific degree of "toe" (misaligned to aim forwardly towards or away from each other) and in the vertical plane to have a specific degree of "camber" (misaligned to aim vertically towards or away from each other).
Checking alignment of wheels using the present gauge is done from the perspective of the wheel's disc brake rotor B, which is necessarily precisely planar with the wheel. In the preferred embodiment shown in Figs 10-15, several equal length extension rods 1 having magnets la at each end are used. The inboard ends of these rods 1 pass through wheel openings D' and attach to rotors B. Plate 2 rests on ground G and attaches to the outboard ends of these rods 1. Plate 2 is therefore planar and parallel to rotor B and to wheel A and serves as the reference surface onto which alignment indicators are mounted to conduct the wheel alignment check.
Two alignment arms 2a have three mounting magnets 54 at their inboard end that hold arms 2a planar to plates 2. The outboard ends of alignment arms 2a have lasers 3, levels 12, and perpendicular tire abutment arms 20. The lasers 3 and abutment arms 20 are spaced identically on each arm 2a. In manufacture, the lasers 3 are adjusted and locked so as to aim perpendicularly dead center into each other's lens when the two arms 2a are in precise mirror alignment with each other.
In use, abutment arms 20 each touch the outer circumference and leading edge of their respective wheel A. Abutment arms 21 are used to contact the rear circumference of their respective rotor B after the wheels are removed.
Each arm 2a may have a support 2b which can be set to a same arbitrary height, and/or, to the same height above ground G as hole 53 (or other shaped apertures such as horizontal and vertical slots) in plate 2. Optional locating pin 22 on arm 2a can then engage hole 53 which makes arms 2a level with ground G as indicated by level 12. The pin 22 and hole 53 can be used to best advantage when the workspace has smooth and level ground G.
The laser's beam 4a cross the vehicle towards opposite targets 51 which have as their center the the other laser's emitting lens 3a. The measured amount of deviation 11 of the laser dot 10 (i,e., a red dot) from the center of the target (laser lens 3a) indicates that wheel's state of alignment. If the arms are horizontal to check for "toe", the effective deviation 11 will typically be in front of or behind the target center and will show "toe-out" or toe-in"
respectively. If the arms 2a are vertical the effective deviation l la will typically be below or above the center of the target and will indicate "positive camber" or "negative camber" respectively.
Because the plate 2 is planar with rotor B and wheel A, the alignment arm 2a is also planar therewith and will in fact show both toe and camber when in either the horizontal or vertical position. However the gauge's accuracy is increased when the two checks are made in separate horizontal and vertical positions.
As shown in Fig 16, measuring deviation 11 (value D) and arm spacing 100 (value S) provides the two values for a ratio (11:100 or D/S) the resultant of which is the SINE (a number) of the wheel's angle. Published trigonometric tables or a calculator is used to convert the SINE number to the wheel's actual angle.
When it is shown that alignment is required, the vehicle H is jacked up via its suspension arms (so that the wheel's angles are not altered) and the wheels are removed to gain access to their adjustment means (bolts and nuts). With the wheels off, the two gauges are reassembled to the exposed rotors and adjustments made to bring the laser dots 10 into conformity with the vehicle's alignment specifications.
With the wheels off, extension rods 1 may have inboard clamp means lc to firmly grasp the rotor B during adjustment, and, rear abutment rod 21 is used to locate against the rear of the rotor B. Several precision-spaced placement holes for abutment arms 20, 21 may be furnished along the arm 2a as shown in Fig 10. A cutout in plate 2 (Fig 11) will allow arm 2a and abutment rod 21 to reach smaller diameter rotors B.
Fig 12 on the left side shows how a mirror 101 may be used in conjunction with a transparent end 103 on alignment arm 2a to direct a reflected laser beam 102 towards a mechanic adjusting a wheel's alignment for remote viewing of the alignment progress. The mirror 101 and/or arm 2a may be marked to show the zero point when the arms 2a are parallel. Other markings on the mirror 101 and on targets 51 may be used as a ruler to measure deviation 11 a.
A two-way mirror with the laser 3 behind it could also be used to effect the same remote viewing (not shown).
Alternatively the lasers 3 may be located above and below the center line of each respective arm 2a so that the beam 4a is visible on the target arm 2a and not obscured by its laser 3, as shown in Fig 19. Abutment arms 20, 21 may have a broad flat shape as shown in Fig 7 to more accurately locate tangentially to the leading/trailing edge of wheel's/rotor's periphery. Also an angle plate or post may be placed on the ground in front of the wheel so as to contact the wheel's leading edge and the abutment arm then brought into contact with it (not shown).
Further the abutment arm 20 may be removably attached so that it can be quickly repositioned to become abutment arm 21 to contact the rear of the brake rotor. In addition, the alignment arms 2a may be of equal length (distance from outboard laser lens to the inboard end) and long enough so that in the vertical mode, the lower ends of arms 2a each contact the ground G (not shown) serving the same positioning/locating purpose as abutment arm 20 and eliminating the locator pin 22 and abutment arm 20.
Figure 20 shows how a common hardware store magnet inclinometer may be attached to the plate 2 so as to measure wheel camber without the use of arm 2a.
Figure 21 diagrammatically shows how a common distance measuring unit laser 101 having emitting lens 3a and with associated calculator 105, may be incorporated into one alignment arm to measure the distance between the two alignment arms 2a so as to quickly compute the wheel angle based on the ratio of distance 100 (Fig 16) and deviation 11. This laser distance measuring may be integrated into existing laser 3. The calculator 105 may also be connected to laser 101 such that the laser-measured distance 100 will be automatically inputted, ready for input of the deviation 11 into the calculator 105. The angle is then displayed by the calculator 105. In greater detail, the calculated result of the ratio deviation 11 divided by distance 100, results in a number which is the ARC SINE (ASIN) of the angle between the two wheels.
Stated otherwise, the calculated ratio result is a number that is the SINE
value of the wheels angle, such that, from a common table of trigonometric values, the SINE value number can be looked up in SINE Tables and across from that number, the angle can be read.
In another embodiment exemplified by Fig 13, the alignment arm 2a of the preferred embodiment is split into two pieces 63, 64 joined together by linear bearing 60. This allows the measuring end 63 (comprising laser 3 and abutment arm 20) to be quickly adjusted, as shown by arrows 61, to bring abutment arm 20 to contact the tire, Further, a second linear bearing 62 may be used to separate the attachment end of alignment arm 64 from its carrier 55 (which attaches or is part of plate 2). This bearing 62 allows split alignment arm 63, 64 to move vertically, as shown by arrows 64. A second support 2b may be added and knobs 2m can be used to turn a threaded support 2b to adjust arm 63, 64 level and to adjust its height above ground for different wheel sizes. A variation of this embodiment shown in Fig 14 also includes keeping the one piece alignment arm 2a and using a double action linear bearing 70 attached to carrier 55 which is magnetically or otherwise fixed to plate 2, This arrangement allows alignment arm 2a to be moved friction free in both required directions 70 quickly and accurately. Thumb screws (not shown) may be added to bearing 70 to lock arm 2a when it is in position.
In yet another embodiment shown in Fig 15, a rotating bearing 80 between Garner 55 and plate 2 allows Garner 55 and arm to be rotated 81 for leveling or for moving to/from horizontal/vertical position, while linear bearing 70 provides fore and aft motion 61 of arm 2a to bring abutment rod 21 to contact wheel A as required to check wheel alignment.
Fig 16 shows the measurements 11, 100 (exaggerated for clarity) needed to calculate the degree of toe or of camber of a wheel using the present invention. Lasers 3 project beams that deviate from dead center by deviation 11 which is made equal on each side by turning the steering wheel; right and left alignment arms have a spacing 100. By way of a "toe alignment"
example, if deviation 11 measures 1 inch and spacing 100 measures 50 inches then each wheel's "toe" angle is that angle whose SINE is 0.020 (1-50). From Trigonometric SINE
Tables this angle is 1.6 degrees (or 1 degree 10 minutes) per wheel, or 3.2 degrees total toe-in.
Table 1 below is a partial reprint taken from the Internet of wheel alignment specifications for a Dodge Neon car (http://www.neons.org/neontsb/TSB/02/020694.htm).
Table 1 FRONT WHEEL ALIGNMENT
TOTAL TOE 0.30° IN TO 0.10° OIJT
CAMBER -0 4° TO +0 4 Thus for this particular vehicle using the above example, the wheel "toe"
alignment is incorrect there being excessive toe-in. Adjusting the vehicles steering arms (tie rods) until the deviation 11 measures, say, zero inches, would bring this vehicles alignment to within factory specifications. Likewise for camber.
In Fig 2 a wheel has wheel nuts or studs G and center hub C. Disc brake has rotor B and caliper E attached with bolts F. Disc brake rotor B runs planar with a wheel A
since they are both accurately mounted on the same axle (not shown). With the wheels A on the ground, access to the rotors is through openings D' such as those between spokes D
common in alloy wheels or through the round vent openings in plain steel wheels (not shown).
In all Figs extension rods 1 are equal length and their inboard ends contact the brake rotors B. The inboard ends of rods 1 may attach magnetically or by clamp means lc as in Figs 6 and 9.
Fig 1 shows how plate 2 (sheet steel) is held planar to rotor B using at least three extension rods 1. Plate 2 then becomes the surface onto which laser or other sighting or measuring tools can be mounted. Plate 2 may be of different sizes or have suitable cutouts to adapt to larger and smaller vehicle rotor diameters Extension rods 1 are equal-length and have strong magnets la (rare earth magnets) at each end. Where the rotor B is smaller than the circle pattern of the vent holes of a wheel, an offset lg shown in Fig 4 can be used on the inboard end of rod 1 so that the magnet la on the offset contacts the rotor B.
Once the rods l and plate 2 are assembled onto the rotors B of the wheels A to be checked for alignment, various types of indicator devices may be attached to plate 2 which is now planar and parallel with the wheel A.
In a simpler embodiment, laser 3 is rotatably attached by magnetic or other means such as a bearing to plate 2 at the center of the plate 2 so as to project a horizontal beam 4, a vertical beam 4a, or a angled beam 4b (as shown in Figs 1, 2, 3) toward a target such as a standing horizontal ruler Sa which may be positioned on stands (not shown), or toward floor targets Sd parallel with, and alongside the vehicle, or towards floor target Sb which is perpendicular to and underneath the vehicle, or upwards towards an overhead suspended target Sc.
With each wheel's laser cooperatively aimed, the alignment can be determined by measuring the relative position of the respective laser dots. For example, if the vehicle's factory stated track (wheel spacing) is 60 inches and the lasers are 5 inches beyond the track on each side but the laser beams are 59 inches apart on a target close to the wheel, then a toe-in of 1 inch exists at target distance. If the target is a greater distance from the laser, then the converging or diverging effect of target distance from the laser is calculated according to that distance and the state of the wheel's alignment is thereby determined. The same applies for both toe and camber measurements.
In another embodiment alignment arms 2a are attached to plates 2 magnetically or by other means. In Figs 7, 8, 9 the arms Za are clamped to bars if which in turn are attached to the rods 1. Clamp screw 2c allows arm 2a to move in cage ld while support 2b is set at, or close to, wheel center height and locked with thumb screw 2c thus allowing arm 2a to be leveled (according to level 12) and then clamped to bars if with thumb screws 2c.
Fig 17, 18 show the simplest embodiment comprising a single extension rod 1 to be inserted through wheel opening D' to contact rotor B with magnet la on the inboard end and a laser lamp 3 on the outboard end. Either end can be arranged with bearing means to enable the laser 3 to rotate 3a in plane and beam its light 4a towards suitable targets such as Sa, Sb, Sc and Sd in Figs 1-3. The larger the diameter of magnet la the better, so as to bridge a scored or grooved rotor surface. This embodiment can also have an offset end as shown in Fig 4.
In Fig 18 the rotor is shown without caliper E or wheel nuts for clarity.
Plate 2 may have ball feet (not shown) to allow easy positioning on ground G
and may be weighted after installed to prevent unwanted movement.
Of course all magnet attachments described above could be replaced by other means such as threaded fasteners, suction cups, clips, clamps, mechanical interlocks, and the like.
Alignment arms 2a and their respective plates 2 could be a one piece assembly such that the assembly is attached to extension rods 1 in a horizontal or a vertical mode to gauge the above mentioned wheel/rotor alignment angles.
In another embodiment, the lasers 3 may be mounted on a rotatable degree dial 120 with angular divisions 121 and a zero index mark 122 on alignment arm 2a. These degree dial's show zero angle when lasers 3 project their beam 110 perpendicularly and on to each other's lens 3a. When the gauge 120 is attached to the vehicle and a horizontal laser dot deviation 11 is present on targets 51, the degree dial 120 is rotated to bring the dot back horizontally to center (i.e., lens 3a) and the vehicle wheel's angle read from the dial markings. The alignment arm could also have its end section holding the laser 3 rotatable for centering the dot in the vertical plane. this end section could also have angular markings and an index mark to read off the vertical angle, or camber, of the wheel when the end is rotated to bring the dot to its vertical center.
It follows from the aforementioned disclosure that other surfaces that are planar to the wheel may be used with the present invention to check alignment, surfaces such as:
areas on the wheel itself; the wheel's drive flange or hub; the wheel mounting studs or holes, the drum brake drum, these providing alignment reference with the wheels still on the vehicle, and, providing working clearance from the vehicle's bodywork for unobstructed gauging.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A gauge for indicating the alignment of a vehicle, said vehicle having at least one alignable rolling assembly, said rolling assembly including a wheel and/or a brake with at least one flat surface thereon, said flat surface being planar with the plane of rotation of said rolling assembly, the gauge comprising:
at least one extension rod having a first inner end portion perpendicular to said rod, said first inner end portion attachable to said at least one flat surface, a second outer end portion perpendicular with said first rod, projection means attached to said second outer end portion, said projection means projecting a path planar with said at least one flat surface, target means cooperatively positioned with said projection means, the arrangement being such that the alignment of said wheel is determinable by said path projected on said target.