FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
A device for measurement of Axle Skewness of a Trailer and method of
measuring thereof
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Babalal Sahebji Mulani, Narayan D Jadhav and N. Kamaljeet
All Indian nationals
of TATA MOTORS LIMITED an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
This invention relates to a device and more particularly to a gauge, which will be used for the axle skewness measurement of vehicle.
BACKGROUND OF INVENTION
In automobiles, tire life is the most concerning factor for the owner of vehicle in order to have lowest possible operating economy. This is very much true for the commercial vehicles fleet owners having bulk number of tires usage with its considerable operating cost. To avoid any of the non-uniform wear on the tire, the steering geometry and axle skewness adjustment of the vehicle should be done in given intervals of kilometers. The improper alignment of axles with respect to each other and chassis of vehicle is called as axle skewness. This misalignment will cause continuous pulling on either side of vehicle resulting in non-uniform wear on the tires. This invention describes a simple and robust gauge, which can be used for axle skewness measurement of vehicle.
SUMMARY OF INVENTION
The main object of this invention is to provide a device for enhanced accuracy in the measurement of axle skewness of vehicle.
Yet another object of this invention is to provide a device having simple in construction and cost effective.
Yet another object of is to provide a device having better performance.
According to present invention a device for axle skewness measurement of a vehicle comprising, a displacer having internal threads and a outer ring at one end, said outer ring located in a collar, a main screw having outer threads and threaded to said displacer, a plurality of cross links hinged to said collar, a plurality of fingers hinged at end of said main screw, the other end of said cross links are hinged to said fingers, a locator provided

at the end of said main screw and a vertically located marker in a bracket connected to said collar.
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 shows schematic of device for axle skewness measurement of a vehicle.
Figure 2 shows the plan and elevation of a trailer
Figure 3 shows the attachment used for connecting a sensor or receiver on a king
pin.
DETAILED DESCRIPTION OF INVENTION
Referring now to the drawing wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.
The device for axle skewness measurement of vehicle is basically a mechanical gauge shown in figure 1. For the measurement of axle skewness the vehicle needs to be parked on a flat, horizontal surface. This device can be used for the vehicles having any number of wheels. To measure the axle skewness the reference points needs to be marked on the surface by using said device, which will represent the respective wheel locations of vehicle. After marking the reference points from each vehicle with the help of said device, the vehicle needs to be moved from the marking area.
Now referring to figure 1, wheel rim edge (15) and wheel hub (16) are the part of vehicle wheel over which the device for axle skewness measurement of vehicle will be fitted. A displacer (1) is a hollow tube with internal threading along the length to which a displacer handle (12) is fitted at the end. The displacer handle (12) is fitted on the displacer such a way that its center axis is perpendicular to the center axis of a displacer (1). The displacer (1) is having an outer ring (4) at its other end, which can be fitted in a collar (3). The main screw (2) is a hollow metal tube with the external threading on its surface along the length. The main screw (2) center axis is

matching with the center axis of displacer (1). The thread size of displacer (1) and main screw (2) are same by which the displacer (1) can be fitted over the main screw (2). The main screw (2) is fitted with a locator (13) at its outer end axially. The locator (13) is a metallic device with a pointer at its one end, which will touch the hub frontal area during the measurement. The locator (13) can be moved along the axis of main screw (2) to maintain the constant distance between each wheel to be measured with the help of markings done on its surface. The locator (13) is fitted in the end portion of main screw (2) in such a way that its axis is coaxial with the axis of main screw (2). The main screw (2) is also fitted with an inclinometer (11) on its top surface. The longitudinal axis of inclinometer (11) is matching with the axis of main screw (2). At least three fingers (5) are provided, one end of which is pivoted on a finger pivot (14) while the other end is fitted with a finger tip (7). The finger pivots (14) are fitted on the main screw (2) peripherally with an angle of 120 degrees from each other. The finger pivot (14) hole center-axis is perpendicular to the center axis of main screw (2) so that fingers are hinged to be rotated in a plane parallel to the axis of the device. The finger tip (7) is provided with the groove by which the finger (5) will have a firm grip over the wheel rim edge (15). At least three cross links (6) to transfer the movement of collar (3) to fingers (5) is provided such that one end of cross link (6) is pivoted on the finger (5) link and the other end is pivoted on the collar pivot (8). A collar (3) is a metallic disc having inner 'U' groove, which can be fitted over the outer ring (4) of a displacer (1). A circular relative motion between collar (3) and outer ring (4) is possible, where the collar (3) will be in stationary position. The collar (3) center axis is matching with the center axis of main screw (2). A marker bracket (18) is fitted at the bottom portion of the collar (3) whose longitudinal axis is parallel to the center axis of main screw (2). A marker (9) is having a tip with the help of which a reference mark can be created on the flat, horizontal surface over which the vehicle is parked. The marker center axis is perpendicular (vertically located) to the main screw (2) center axis. A stopper is provided at the top of marker to arrest the excessive movement.

Now referring to figure 1, for the fitment of said device on wheel rim edge (15), the displacer (1) needs to be rotated in anticlockwise direction with the help of displacer handle (12). The main screw (2) or fingers (5) can be held during the fitment as these are the non-rotating parts of a device. The anticlockwise movement of displacer (1) will cause a linear movement of it due to the threading. The outer ring (4) of displacer (1) will be also rotating in the inside grove of collar (3). The collar (3) will be in stationary position but due to linear movement of displacer outer ring (4) caused by anticlockwise rotation will push the collar (3) towards outside. This linear movement of collar (3) will also push the cross link (6) towards outside resulting in expanding the fingers (5) peripheral diameter. This movement of finger (5) will push the finger tips (7) to hold the wheel rim edge (15) firmly. The horizontal application of said device can be confirmed with the help of inclinometer (11) fitted on the main screw (2). Fingers (5) needs to be readjusted if the horizontal fitment of said device is not observed. The three fingers holding a wheel rim circle will result in getting the wheel rim or wheel hub center directly. The axis (17) of the device will match with the wheel rim or wheel centre of the vehicle. The locator (13) can be then pulled through main screw (2) end portion and can be touched to the wheel hub surface, which will be the center of the hub. The marking done on the locator (13) will define the distance between said device and the hub surface, which can be replicated on the other wheels of vehicle to be measured. A marker (9) can be then dropped on the surface to mark a reference point of wheel under measurement.
The complete procedure described above needs to be repeated for each wheel of the vehicle, which will form a matrix of measuring points. After marking all reference points of all wheels the vehicle will be moved from the measuring surface and then the further measurement of axle skewness of vehicle can be carried out.
Referring to figure 1, in addition to the arrangement described earlier the device can also be fitted with a laser marker or pointer instead of a mechanical marker (9). The laser can be fitted perpendicular to the axis of displacer handle (12). The procedure for the fitment of the device over the wheel rim will be same as in case

device with marker but instead of marking a reference point with the marker a laser point can be plotted on the ground for the marking. The clamping arrangement for mounting the device on the wheel rim can have at least three jaws and maximum four jaws which can hold the rim firmly and achieve the matching of centre of axle hub with the centre of displacer handle or a laser or a non contact type distance measurement sensor.
Referring to figure 2, the device can be utilized for the measurement of axle skewness of a trailer having a king pin (21) at the front portion and single/ two/three axles at the rear portion. It is of utmost importance to have an equal distance between the kingpin (21) and the left side tire (25') of first axle (22) with the distance between the kingpin and right side tire (25) of first axle (22). Once the above distances are ensured for equal value, the first axle (22) can be taken as a reference and the measurement for the second axle (23) and third axle (24) can be done to have parallelism between all three axles. The measurement and correction of the trailer axle skewness must be done to avoid the vehicle pulling and trailer axle tire dragging.
Referring to figure 3, shown a device for locating the kingpin centre having a magnetic disc (31) with the diameter equal to the diameter of the Kin pin (21) bottom. This magnet will have a provision for the mounting of the laser unit and or a receiver (32) of a non contact type distance measurement device in the axis line. This device will be mounted below the king pin (21) before the start of the measurement and the king pin location can be mounted on the ground with the point defined by a laser which is perpendicular to the ground.

WE CLAIM
1. A device for measurement of axle skewness of a trailer comprising:
a hollow tube with internal threading along the length configured to coaxially fit over a main screw member with external threading on its surface along the length;
a handle member fitted on one end of said hollow tube to provide rotary movement to said hollow tube;
an outer ring provided at an end away from the handle member, said outer ring being configured to be fitted in a collar;
a locator fitted axially on said main screw member at its outer end, said locator having a pointer at its one end, which will touch a wheel hub frontal area during the measurement;
plurality of protruding finger members, configured to hold wheel rim edge of the vehicle;
a motion transferring means to transfer linear movement of said collar to expand said finger members;
an inclinometer fitted on top surface of said main screw; and
a marker to create/plot a reference mark on a horizontal surface over which the vehicle is parked, axis of said marker being perpendicular to the axis of said main screw member.
2. The device as claimed in claim 1 wherein said marker being a laser marker or pointer.
3. A method for measuring the axle skewness of a trailer comprising the steps of:
marking a reference point on the horizontal surface of first wheel axle using a marker or plotter located in the line of axis of the wheel hub and positioned perpendicular to the axis of the wheel hub;

repeat the above step for each wheel axle of the vehicle to form a matrix of measuring points;
marking a reference point on the horizontal surface below the king pin of the trailer by a device located in the axis of the king pin;
measuring surface distance between the reference point for king pin and first left and right wheel axis;
measuring the surface distance between the first wheel axis and remaining wheel axises;
and performing further measurement of axle skewness on said trailer.
4. A device for measurement of axle skewness of a vehicle substantially as hereinabove described with reference to the accompanying drawings.
5. A method for measuring the axle skewness of a vehicle substantially as hereinabove described with reference to the accompanying drawings.