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 and method for measurement of axle skewness
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 trailer.
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 nonuniform wear on the tire, the steering geometry and axle skewness adjustment of the vehicle and trailer 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. The measurement of axle skewness of trailer needs to be done in such a way that all trailer axles must be parallel to each other and also to the last axle of a tractor. In case of trailer as a standalone it was very difficult to measure the axle skewness of trailer axles as one has to take the first reference from the trailer king pin. The distance between the trailer king pin and the trailer axles vary from 5-7 meters. On the other hand the king pin is mounted at the central portion of trailer front area hence it is very difficult and inaccurate to measure the left and right side distance between the king pin and first axle tires with the other trailer components like Side Upper Protection Device (SUPD) etc coming in between. The current measurement with the help of a measuring tape or a rope was found to be very inaccurate and hence a need was felt to design an accurate trailer axle skewness measuring system. This invention describes a simple and

robust gauge, which can be used for axle skewness measurement of trailer and vehicle axles also.
SUMMARY OF INVENTION
The main object of this invention is to provide a device for enhanced accuracy in the measurement of axle skewness of trailer and 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 the present invention a device for measuring axle skewness of a vehicle comprising, a main shaft with left and right hand threaded portions, a first and second plates threadably mounted on the left and right threaded portions of said main shaft, a pair of clamp rods attached to each of said plates, a pair of guide rods attached to one of said plate and configured to guide the other plate, a sensor/receiver mounting plate attached to said shaft, said mounting plate has extensions with guide bushes at ends to guiding in said guide rods.
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 shows the schematic of device for axle skewness measurement of a
vehicle.
Figure 2 shows the receiver mounting device for axle skewness
measurement
Figure 3. Shows the plan and elevation views of a trailer.
Figure 4 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 trailer and vehicle is basically a mechanical gauge shown in figure 1. For the measurement of axle skewness, the trailer needs to be parked on a flat, horizontal surface. This device can be used for the trailer having any number of wheels. To measure the axle skewness the device shown in figure 1 must be fitted on the wheels of trailer first axle. The device shown in figure 2 will be fitted on the second and/or third axle depending upon the number of axles the trailer is having. The device shown in figure 4 will be fitted at the king pin of a trailer on which the receiver is fitted. With the help of sensor (8') on first axle, the distance between the first axle left and right side with reference to king pin can be measured. Referring to figure 3, once the distances of left and right side between first axle and king pin are ensured as identical (X1=X2) then the second and third axle of trailer can be made parallel with the first axle (X3=X5 and X4=X6). To have no axle skewness of trailer, following condition must be met,
X1=X2 X3=X5 X4=X6

of support plate (4') freely. The shaft (I) is having a knob (6) at its top side end, below which it is supported by another support plate (4) with a through hole (16). The shaft (1) is fitted in such a way that it is perpendicular to the support plates (4') and (4). A pair of moving plates (2, 2') is fitted on the left and right threaded portions of the shaft (1) with the help of bushes (3, 3'). The bushes (3, 3') is having an internal threading which matches with the threading on the shaft (1). The bushes (3, 3') outer diameter is same as the diameter of hole (15) in the moving plates (2,2'). The bush (3') is fitted in the moving plates (2, 2') by the interference fit. The moving plates (2, 2') are also fitted with pair of clamp rods (5) at its both ends. The clamp rods (5) are having a threaded portion at one end which fits in the threaded hole (11) of moving plate (2, 2'). The clamp rods (5) are fitted perpendicular to the moving plates (2, 2'). The clamp rods (5) are having a bend at their other end for having firm clamping on the wheels of the tires. The clamp rods (5) are fitted in such a way that it passes through the holes (10) provided on the support plates (4, 4'). The clamp rods (5) are fitted perpendicular to the support plates (4, 4'). A pair of guide rods (12) is fitted in the moving plate (2) with the help of its threaded end which matches with the threading provided on the moving plates (2) holes (13). The guide rods are fitted perpendicular to the moving plate (2). Further the guide rods (12, 12') pass though the holes (18) on the moving plate (2'). The guide rods (12) are fitted perpendicular to the moving plate (2') and can move freely in the holes (18). The length of the guide rods (12) is chosen in such a way that in no case the moving plate (2') can come out of the guide rod (12). A mounting plate (7) is fixed on the shaft (1) preferably at the half of the length of shaft (1). The shaft (1) passes through the mount plate (7) through the centre hole of mounting plate. The shaft (1) axis coincides with the axis of mounting plate (7) centre hole axis. An internal square grove is provided in the mounting plate hole so that the matching square protrusion on the shaft (1), fit exactly at its centre, and assemble with each other. The

mounting plate (7) is fitted with a sensor (8) at the centre of the plate and in such a way that the shaft (1) axis is perpendicular to the sensor (8) axis. The mounting plate (7) is fitted with the bridge rods (19) to mount the guide bushes (14,14') in such a way that the axis of bridge rods (19) coincides with the axis of the sensor (8). The guide bushes (14,14') are fitted in such a way that the axis of bush coincides with the axis of guide rod (12) and the guide bushes (14) can move freely in the guide rods (12) vertically. The guide bush (14') is fitted with the sensor (8') with the help of clamping arrangement (17). The axis of the sensor (8') coincides with axis of the sensor (8). The clamping arrangement (17) is having two plates with the centre hole through which the screw and nut bolt can be fitted. The sensor (8') is having a matching plate at its end which sandwiches in the two plates of clamping arrangement (17). The Sensor (8') can be adjusted in such a way that it can send the signal to the receiver fitted on the king pin. Once the sensor (8') is adjusted the screw and nut can be tightened to have sufficient clamping and no disturbance in the positioning of sensor (8'). Referring figure 2, the device for the second and third axle of trailer is having a similar arrangement of components like device to be fitted on the first axle of trailer except the clamping arrangement (17) and the sensor (8') which is fitted on the clamp plate (7). The device to be fitted on the second and/or third axle will have a receiver (21) which received the signal from the sensor (8) of the first axle device. The receiver (21) is fitted in such a way that it is exactly at the centre of clamp plate (7) and its axis is perpendicular to the shaft (1).
Referring to figure 4, a device for fitting the sensor (32) on the king pin (30) is having a magnetic disc (31) with the diameter same as the diameter of king pin (30). The sensor (32) is fitted on the magnetic disc (31) in such a way that the axis of sensor coincides with the axis of the magnetic disc (31). During the measurement the magnetic disc (31) will be fitted on the

king pin (30) by matching king pin (30) and magnetic disc (31) outer diameters.
In the axle skewness measurement process of trailer, the device shown in figure 1, will be fitted on one of the side of first axle. To fit the device all four clamp rods (5) can be expanded similar to the jaw by rotating a knob (6). The rotation of knob (6) rotates the shaft (1) which in turn shifts the moving plate (2) and (2') with respect to the clamp plate (7) as the shaft (1) is having left and right hand threads on two half portions respectively. The moving plate (2') moves in the guide rod (12) to avoid the rotation of moving plate (2') and also moving plate (2). Once the device is firmly fitted on the wheel of first axle, the sensor (8') can be adjusted by the clamping arrangement (14) in such a way that it can send the signal to receiver (32) fitted on the king pin. The device shown in the figure 2 can be fitted on the second/third axle with the similar procedure mentioned above. The sensor (8), receiver (32) and receiver (21) can be made ON by providing the necessary power supply. The sensor and receivers can be any non-contact type measurement devices. A connection from the sensor and receiver are connected to a computer which receives the measurement reading for all the dimensions shown in figure 3 i.e. X1, X2, X3, X4, X5, and X6 once the fitment and measurement procedure is repeated on the other side of the trailer. The axle skewness adjustment screw fitted on the trailer axles can be adjusted till the dimensions requirement described in figure 3 is met.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

We claim
1. A device for measuring axle skewness of a vehicle comprising, a main shaft with left and right hand threaded portions, a first and second plates threadably mounted on the left and right threaded portions of said main shaft, a pair of clamp rods attached to each of said plates, a pair of guide rods attached to one of said plate and configured to guide the other plate, a sensor/receiver mounting plate attached to said shaft, said mounting plate has extensions with guide bushes at ends to guiding on said guide rods.
2. The device for measuring axle skewness of a vehicle as claimed in claim 1 wherein said clamp rods are supported by support plates mounted on said main shaft.
3. The device for measuring axle skewness of a vehicle as claimed in claim 1 wherein a sensor/receiver is attached on said mounting plate in such a way that the axis of the sensor is perpendicular to the axis of the shaft and axis of said extensions are coincide with the axis of the sensor.
4. The device for measuring axle skewness of a vehicle as claimed in any one of the preceding claims wherein a sensor is attached to said guide bush with axis perpendicular to the axis of the shaft.
5. The device for measuring axle skewness of a vehicle as claimed in claim 1 wherein a knob is attached to said main shaft for rotating to move the plates axially to adjust the clamp rods to fix the device on the wheel.
6. A method of measuring and correcting the axle skewness of a vehicle comprising the steps of; clamping the device as claimed in claim 1 to 4 on the wheels of first axle of a tailor, clamping the device as claimed in claim 1 to 3 on the wheels of second axle of a tailor, attaching a receiver device on the king pin of tailor, measuring the distances between the kingpin and centre of left (XI) and right

(X2) wheels of the first axle, measuring the distance between the first and second axle left (X3) and right (X4) wheels, aligning the axles of the tailor in such a way that X1 = X2 and X3 = X4.
7. The method as claimed in claim 6 wherein said king pin receiver device having a magnetic disc for attaching to said king pin and a receiver attached to said magnetic disc.
8. A device and method for measuring axle skewness of vehicle as herein described with reference to accompanying drawings.