FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF INVENTION
Addition Of Small Reduction Gear Assembly On Steering Column To Reduce Steering Effort
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
Mr. Laxman K.Yadav, Ms. Charu Saxena
And Mr.Amol Majgaonkar.
All are 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 an Addition of small reduction gear assembly on steering column to reduce steering effort. This invention is applicable for all kinds of vehicles ranging from LCV, MCV, HCV, MUV, Passenger Cars and others.
BACKGROUND OF INVENTION
Currently, two basic types of steering systems are used with either mechanical otherwise Manual Steering or Power assisted Steering. In the manual steering vehicle generally one has to make more number of turns than power steering to compensate the steering effort, but still the effort is high in manual steering vehicles because of Front Axle Weight (FAW) which is more in many cases, and during parking condition the steering effort will be very high, so it reduces the comfort of passengers.
Currently passenger cars having Rack and pinion gear and Collapsible Steering Column, some vehicles may have different type of gear but all vehicles have steering column including LCV, MCV, and HCV. Primary function of the steering system in automobiles is to provide the directional stability and driver control on vehicle with less effort. These systems may be conventional mechanical systems.
Also in current mechanical steering vehicles, more number of turns are provided than power steering to compensate the steering effort, but still the effort is high in mechanical steering vehicles because of FAW (Front Axfa Weight- which is more in many cases), and during parking condition the steering effort will be very high, which will reduce the comfort level of passengers. Steering Effort is very sensitive parameter for comfort condition of driver, if the steering effort is high, then driver feels uncomfortable and it may cause accidents.
The steering effort of vehicle should be determined on the base of the work characteristic of the steering system F=f (5H) expressed by the relationship between the control effort on the steering wheel F and its turn angle 5H. This relationship


should be obtained by the measurement of the force F and the angle 5H during the determined change of the direction of vehicle driving with the constant speed.
The start of the measurements and records of the force F and angle 5H should be followed after the vehicle drove on the circle at the maximum turn of the steering wheel.
Starting from this position the steering wheel should be turn with the constant speed (d5H/dt) in opposite direction until it accomplishes the full opposite position. After the temporary stop of the steering wheel the direction should be changed maintaining the same constant rotary speed to the maximum original turn angle.
During these measurements the absolute rotary speed of the steering wheel should be selected from the range between 20 degrees per second (7s) to 50 degrees per second (7s) and kept constant in both directions of the steering wheel.
Starting from the maximum turn of the steering wheel in right direction at least two measurements should be taken and then similarly it should be done for maximum turn position in left direction.
In parking condition the steering effort is very high, and if the vehicle is in full laden condition then it will increase slightly. In parking driver should turn steering at right lock to left lock continuously to adjust the vehicle in parking slot, at that time the vehicle speed is very less and due to this the friction between the tire and ground is more, so always steering effort is maximum at the time of parking of the vehicle.
OBJECTS OF INVENTION
The main object of this invention is to reduce the steering effort or the driving effort and improve the handling of vehicle, also it will reduce the accidents which caused by changed ergonomics.
Yet another object of the invention is to provide good driving feel.


Yet another object of the invention is that to provide pure mechanical linkages which gives safety and avoid the chances of accidents, which can be caused by failure of power steering.
Yet another object of the invention is that to reduce the torque at steering wheel, as well to produce more torque to input of rack and pinion.
Yet another object of the invention is that to provide a cost effective solution and ease of maintenance.
BRIEF DESCRIPTION OF INVENTION
To reduce the steering effort, either it is required to increase the diameter of steering wheel or to increase the number of turns. If there will be increase in the steering wheel diameter, then it will disturb the ergonomics, so if provision of addition of small reduction gear assembly on steering column is done, then it will greatly reduce the steering effort, using the same rack and pinion gear.
This assembly contains 2 gears and 2 pinions, with the pinion pair having less diameter than gear. One pinion and one gear can be generated on shaft as an integral gear and another will acts as a separate part.
The casing assembly will have provision of bearings and fasters. The integral gear will be held at one end and the other gear will assemble on steering column shaft. For introducing this change it is required to split the steering column shaft. The lower casing assembly will be fixed on column tube, and upper will be assembled on lower casing assembly by using fasteners.
Accordingly the present invention discloses a steering assembly for a vehicle comprising: a steering wheel; a steering column assembly having an upper steering column shaft and a lower steering column shaft; a first gear and a first pinion provided on an integral shaft; a second gear connected to said lower steering column shaft and a second pinion connected to said upper steering column shaft; wherein


said first gear provided to be in a meshing arrangement with said second pinion and said first pinion provided to be in a meshing arrangement with said second gear.
STATEMENT OF INVENTION
This invention relates to a steering assembly for a vehicle comprising; a steering wheel; a steering column assembly having an upper steering column shaft and a lower steering column shaft; a first gear and a first pinion provided on an integral shaft; a second gear connected to said lower steering column shaft and a second pinion connected to said upper steering column shaft; wherein said first gear provided to be in a meshing arrangement with said second pinion and said first pinion provided to be in a meshing arrangement with said second gear.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 shows a complete assembly of a device.
Fig.2 shows the exploded view of the device.
Fig.3. shows the detailed sectional view of the device with complete idea of the
mechanism.
DETAILED DESCRIPTION OF INVENTION
Referring to figure 1. and figure 2. the device of reduction in steering effort and improvements in the vehicle handling (5) which is mounted on steering column assembly (2). This assembly contains two gears and two pinions .The pinion pair is having less diameter than gear. One pinion and one gear can be generated on shaft on the Integral gear and second pinion (8) and second gear (9) will act as a separate part. The casing assembly.will have provision of bearings and fasteners (11). The integral gear (7) will be held at one end and the second gear will assemble on steering column lower shaft (4). For introducing this change it is required to split the steering column shaft in two parts, upper column shaft (3) and lower column shaft (4). The lower casing assembly (6) will be fixed on column tube by suitable joining


process such as welding and upper will be assembled on lower casing assembly by using fasteners (11) as shown.
The upper column shaft (3) having splines for mounting second pinion (8) and circlips (10) provided for locking the second pinion (8) on upper column shaft (3). Similarly, the Lower column shaft (4) having splines for mounting second gear (9) and circlips (10) provided for locking the second gear (9) on lower column shaft (4). The fasteners joint the two casings and held complete gear assembly. The dust cover (5a) will provide on gear assembly device (5) to protect the assembly from dust, foreign particles etc.
Introduction of Gear Assembly will give following sequence of motion transfer
• Steering wheel (1) to steering column upper shaft second pinion (8) then to integral gear (7) after that to steering column lower shaft second gear (9) to column assembly (2) which contains the intermediate shaft and connects universal joints to Pinion gear which then connect to rack gear and finally to wheels.
• By keeping the same steering gear ratio in steering gear assembly ,the steering effort will reduced, it will increase the number of turns of steering wheel (1) by keeping same lock angles (left and right).
Assembly procedure for the steering effort reduction device.
Referring to fig.2 and fig. 3 the device for reduction in steering effort and improvements in the vehicle handling (5) will be mounted on steering column assembly(2), by suitable joining process such as welding. The second gear (9) and second pinion (8) will mount on Lower column shaft (4) and upper column shaft(3) respectively, the circlips (10) will assembled above and below to the second gear (9) and second pinion (8) to avoid linear moments of gear.
The integral shaft gear(7) will mesh with second gear(9) and second pinion (8), such a way that second pinion (8) will mesh with gear on integral shaft and second gear(9)
3 0 MAR 2009

will mesh with pinion on integral shaft gear(7), it will keep the same reduction ratio and same direction of rotation of steering wheel(l) with actual turn. The dust cover (5a) will be assembled on gear assembly (5), and finally the steering wheel (1) will be assembled.
This mechanism will reduce the steering effort, also it will help for reducing steering effort in power steering vehicles to be converted in to mechanical steering or failed power steering vehicles.
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 steering assembly for a vehicle comprising:
a steering wheel;
a steering column assembly having an upper steering column shaft and a lower steering column shaft;
a first gear and a first pinion provided on an integral shaft;
a second gear connected to said lower steering column shaft and a second pinion connected to said upper steering column shaft; wlierein
said first gear provided to be in a meshing arrangement with said second pinion and said first pinion provided to be in a meshing arrangement with said second gear.
2. The steering assembly as claimed in claim 1, wherein a casing assembly, having a lower and upper casing member, is provided to house said gear and pinion assembly, such that a lower casing member is fitted on said lower steering column shaft and an upper casing member is fastened to said lower casing member.
3. The steering assembly as claimed in claim 1, wherein the module of any two meshing gears should be same, and modules of said first and second pinions may or may not be equal, thereby the number of turns given at steering input at a reduced effort, is more than that of the actual required number of turns otherwise.
4. The steering assembly as claimed in claim 3, wherein the diameter of said first and second pinions are lesser than the diameter of said first and second gears.
5. The steering assembly as claimed in claim 1, wherein said upper steering column shaft and said lower steering column shaft comprises splines for mounting said second pinion and said second gear respectively.


6. The steering assembly as claimed in claim 5, wherein circlips are provided for locking said second pinion on said upper steering column shaft and for locking said second gear on said lower steering column shaft.
7. The steering assembly as claimed in claim 1, wherein a dust cover is provided on said gear and pinion assembly to protect from ingress of foreign particles.
8. The steering assembly as claimed in claim 1, wherein said gear and pinion assembly is adapted to reduce steering effort by maintaining the same steering gear ratio and increase the number of steering wheel turns or vice versa.
9. A steering assembly for a vehicle substantially as hereinabove described with reference to the accompanying drawings.
Dated this 30th day of March 2009
TATA Motors Limited By their Agent & Attorney

(Karuna Goleria)
of De PENNING & De PENNING