THE PATENTS ACT 1970

COMPLETE SPECIFICATION

SECTION 10

A DIFFERENTIAL LOCK SYSTEM FOR AN AUTOMOBILE
TVS MOTOR COMPANY LIMITED, JAYALAKSHMI ESTATES, 8 HADDOWS ROAD, CHENNAI600 006, TAMIL NADU, INDIA, AN

INDIAN COMPANY

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THIS INVENTION AND THE MANNER IN WHICH

IT IS TO BE PERFORMED:

This invention relates to a differential lock system for an automobile.
In an "open" differential system, the usable torque is restricted by the wheel with the least traction . A differential lock system locks out the differential action and forces the torque to be split equally between each wheel (or each axle) for maximum traction. Spinning of the wheels is prevented.
Locking of the differential assembly helps increase traction; at the same time it makes steering more difficult on high traction surfaces because it tends to force the vehicle to travel in a straight line. The known lock system is operated manually by the user, when required. In this invention, however, the locking action is provided by synchromesh engagement.
This invention relates particularly to the differential assemblies of three wheeled vehicles, especially to lock the differential function when the vehicle gets stuck in heavy mud, ice and so on and when one wheel is freely spinning.
Reference will now be made to the accompanying drawings
Fig.l illustrating a front sectional view of the embodiment
Fig.2 illustrating a partial back view of a crank shifting mechanism of the embodiment
Fig. 3 illustrating the top view of the embodiment
2

Fig.4 illustrating a partial perspective view of the synchromesh pack of the embodiment
Fig.5 illustrating a specimen of a known differential lock system
In general the differential in a power transmission system of a motor vehicle allows a pair of output shafts operatively coupled to an input shaft to rotate at different speeds while the vehicle is turning and the differential lock is used to lock the differential function when the wheel is spinning on one side.
The known system is illustrated in Fig.5.The crown wheel 1 of a differential unit has a step at one end with dog teeth la arrangement. The engaging dog teeth 2 have the dog teeth 2a arrangement and is connected to an output shaft 3 spline 3a. This engaging dog teeth 3 will be operated manually with a shift rod assembly 4 by a crank lever 5 actuation. When the engaging dog teeth 2 engage with the crown wheel 1 dog teeth lathe torque is given to the crown wheel 1 directly transmitted to the output shafts 3 and 6.
Normally the manual differential lock system is used and it consists of dog teeth arrangement which give more noise and jerk while locking the differential. Also the locking system cannot be engaged sometimes in the vehicle stationary state due to dogteeth misalignment. Thus there is a need
for differential lock system with smoother engagement even in the vehicle station dry condition without noise and jerk. This manual differential system provides a simple and compact assembly.
Referring to Figs. 2 to 4 of the accompanying drawings:

The driven gear 11 of the differential assembly B has an extended shaft lla at one end with external splines lib where the synchroring 19 is connected permanently. The cage assembly 12 of the differential assembly B is connected to the driven gear lias in the known way, such as, by means of bevel gears 13, bevel pinion 14 and spider 16. The entire differential assembly B is supported by two ball bearings 17, IS at both ends. The output shaft 22 is connected on to bevel gear spline 13a, 22c and has two different splines 22a 22b at two places, one of the splines 22b connected with one side of the wheel axle shaft. The synchroring is connected on the synchroring 19. This synchropack assembly is fitted on the shaft with plain plate 23 and circlip 24. The shifting fork 25 is mounted on the engaging gear 21.
The shifting crank mechanism 30 is illustrated in Fig.2.For engagement o'-the lock system the lever 29 will be operated upwards as shown in Fig.2
Fig.3 illustrates shifting crank mechanism arrangement in top view and the shifter guide shaft 26 which engages with shifting fork 25. The shaft 26 has two steps 26a for defining the engaging position , the plunger 27 bolted on cover 31.
When the lever 29 is lifted upwards, the crank 20 rotates in clockwise direction, it moves the engaging gear by moving the fork and engages smoothly with synchrocone 19 and synchroring 20. After the engaging gear 21 engages the differential system is locked and it transmits the torque and
f

speed equally to the shaft, there will not be any differential function after the en gag em ent.
Therefore the differential lock system assembly according to this invention proposes a differential lock system that is very smooth in engagement without any jerk and can be operated at any vehicle speed. It is simple and compact in construction.
It will be appreciated from the foregoing that various other embodiments of the differential lock system proposed herein are possible without departing from the scope and ambit of this invention.