FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)


TITLE OF THE INVENTION
Testing of Interaxle Differential Assembly With The help of Brake Dynamometer On Bench.
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
Bhaskar B Godbole and Pravin A Kathale
both 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 the testing of interaxle differential gears in tandem bogie rear axle. More specifically, it is "on bench testing procedure and set up" of interaxle differential gears in tandem bogie rear axle where, part of the power transmitted from gear box gets transferred to Rear axle through rear forward axle having interaxle differential gears.
BACKGROUND OF THE INVENTION
Figure 1 gives the schematic plan view of first and second rear axle as in vehicle
condition.
In heavy vehicles, where two set of rear axles are used in transmission line, power
from engine (2) gets transferred to gear box (1) and propeller shaft (3) transmit the
power from gear box (2) to input shaft (4) of first rear axle (Rear forward axle) (5)
which again gets distributed to the second rear axle (rearward axle) (6) from out put
shaft (7) of first rear axle, through interaxle differential mechanism.
Interaxle differential assembly is mounted inside the carrier assembly of the first rear
axle. Interaxle differential distributes the power in equal proportion to the first rear
axle and second rear axle so that both the axles becomes live axles and helps the
vehicle to move stable on rough roads by giving better traction.
Whenever wheel mounted on any of the rear axle gets off the road surface or sleeps
(due to ice, etc.) power gets lost through that axle. In such case, driver can connect
both the axles by using the shifter mechanism (differential lock) so that power coming
from the engine will get distributed equally within both the axles and vehicle can
perform well on rough/ bumpy, ice road etc.
The function of interaxle differential assembly is to distribute the power within both
the axles and hence it becomes necessary that interaxle differential gears are strong
enough to sustain that load for its life.
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Presently, no prescribed method is available for testing of differential gears in interaxle differential assembly on bench. Testing of the axles on vehicles in the field is the only available way of getting the confidence on strength of interaxle differential gears which leads to following disadvantages:
• More testing time and also it is costly as this needs total vehicle for testing one
component.
• Need to test on the special tracks (road terrain).
• Difficult to address the failures.
• Difficult to reach the vehicle, if fails in remote area and there by delay in project
program. Proposed set up describe the test method for bench testing of interaxle differential gears.
Components in carrier assembly as shown in figure 2 are Input shaft (1), Input shaft gear (2), Output shaft gear (3), Output shaft (4), Tail pinion of first rear axle (5) and Crown wheel of (6).
OBJECTS OF THE INVENTION
Objective of the proposed invention is to test the interaxle differential gear on bench so that endurance life of the interaxle differential gears in multi axle vehicles can be tested and different failures on interaxle differential gears can be simulated. Advantages of this invention are as follows:
• Testing of the interaxle differential gears will be possible on bench.
• Endurance life of the interaxle differential gears can be evaluated.
• This method allows the interaxle differential gear testing with very simple and easy
set up.
• Different failure modes of interaxle differential components in field can be
simulated and analyzed on the test bench by using this set up and help in reducing
project time.
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In interaxle differential gear set up, suitable size of brake can be fitted on out put shaft so that by giving the actuation, O/P shaft will be locked and unlocked according to actuation of brake.
SUMMARY OF THE INVENTION
Brake dynamometer comprises Brake assembly and brake drum for braking action, Piston and cylinder arrangement to actuate the brake pedal, PLC with pneumatic solenoid valve and pneumatic connections for operation, etc. By implementing said invention for interaxle differential;
• Testing can be done to predict the life of the test specimen.
• Test specimen with any specifications can be tested by changing the brake cycle time.
• Differential action can be achieved of any required percentage.
• Test set up will be easy and involve fewer components.
• Space requirement will be low.
• Electric power requirement for brake set up is almost nil.
STATEMENT OF INVENTION
Accordingly the present invention discloses a test set up for testing of interaxle
differential assembly with the help of brake dynamometer comprising
main motor adapted to give input speed to the interaxle differential assembly through
transmission means;
said interaxle differential assembly is configured for mounting input shaft and output
shafts;
at least two dynamometers are connected to the interaxle differential assembly wheel
ends to provide torque / load;
at least one brake drum configured to be coupled on said output shaft;
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at least one brake assembly configured for applying brake pressure on said brake
drum;
at least one PLC (Programmable Logic Controller) for actuating solenoid valve of
said brake assembly;
at least two step down gear box configured to be mounted on each of the wheel end
sides between said dynamometer and said wheel end facilitated for controlling
dynamometer speed;
facilitated for testing strength of interaxle differential gears of interaxle differential
assembly
BRIEF DESCRIPTION OF THE DRAWINGS
In accordance to the present invention
Figure 1 shows schematic plan view of first and second rear axle as in vehicle
condition. Figure 2 shows the components in the carrier assembly. Figure 3 shows the line lay out of proposed test set up for testing of interaxle
differential assembly with the help of brake dynamometer. Figure 4 shows the set up for brake actuation. Figure 5 shows gear speed before braking Figure 6 shows gear speed after braking
DETAILED DESCRIPTION OF THE INVENTION
Figure 3 gives the line lay out of proposed test set up which consists of main motor (1), test specimen (2), Input shaft of the test specimen (3), Out put shaft of the test specimen (4), dynamometers (5 & 6) one each at both the wheel ends of the test specimen, brake drum (7), brake assembly (8), hydraulic connections (9), brake pedal set up (10), piston and cylinder arrangement and PLC etc. 1) Main Motor: Main Motor was used to give speed input to the test specimen.
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2) Test specimen: Test specimen was first rear axle having interaxle differential assembly. Input shaft (3) and out put shaft (4) are mounted on test specimen and those are the original fitment of the test specimen.
5 & 6) Dynamometer: Two dynamometers, one each for first axle wheel ends were used to provide torque/ load to the test specimen.
7) Brake drum: Brake drum was bolted on output shaft flange of the first rear axle
8) Brake assembly: Hydraulic brake assembly was grounded with proper alignment with respect to brake drum.
9) Hydraulic connections: Hydraulic connections were used to actuate the hydraulic brake by pressing the brake pedal.
10)Brake pedal set up: (refer figure 4) Brake pedal (2) was mounted on the rigid frame(l) and hydraulic connections (8) were given between brake pedal and brake assembly. Brake assembly was bolted on matching brake flange and brake flange was grounded with proper alignment with respect to brake drum. Piston and cylinder arrangement was made to apply and release the brake with the help of brake pedal set up. Pneumatic actuation was given through solenoid valve to piston (3) and cylinder (7) arrangement and solenoid valve was actuated through PLC. Piston will get actuated by actuation of solenoid valve (6) which in turn will press brake pedal and brake will get actuated. Components in brake pedal set up: Base Frame (1), Brake pedal (2), Piston (3), Pneumatic connections from cylinder to PLC (4), PLC (5), Pneumatic solenoid valve (6), Cylinder (7), Hydraulic connections from brake pedal to brake assembly (8), Master cylinder for hydraulic actuation (9), Hydraulic connections from oil reservoir to master cylinder (10) and Oil reservoir (11).
ll)Piston and cylinder arrangement: (refer fig.4) Piston and cylinder arrangement was connected to brake pedal in such a way that it will actuate the brake according to the actuation of piston.
12)PLC: Simple PLC was used to actuate pneumatic solenoid valve of brake set up.
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Working of set up
Required Input speed to the input shaft of the test specimen was given with the help of
main motor (Step down gear box was used in between main motor and test specimen,
to reduce the motor speed up to required speed). Brake drum was mounted on the
output shaft of the test specimen and hydraulic brake assembly was fitted with proper
alignment with respect to brake drum. Hydraulic brake assembly was grounded to
restrict moment and movement of the brake assembly. Left hand side and right hand
side wheel ends were connected to dynamometers (Step down gear box, one each on
both the wheel end sides was used between dynamometer and wheel end to control
the dynamometer speed to required limit).
In normal running, if Input shaft (1) of the first rear axle rotates at the speed N] (refer
fig.5), then the O/p shaft(2) and out put shaft gear (3) and Input shaft gear (4) will
rotate at the same speed Ni where as both the wheel ends will rotate at speed N2 =
Nl/Crown wheel pinion ratio. As soon as the pneumatic solenoid valve gets actuated
through PLC, it will actuate the piston and in turn, brake pedal will get pressed and it
will cause brake drum mounted on output shaft of the first axle to stop. In Fig 5 and 6
Input shaft (1), Out put shaft (2), Output shaft gear (3), Input shaft gear (4) and Bevel
gears (4 nos.) (5).
In this case speeds at different locations will be as below (refer fig.6);
Input speed: Nj.
Output shaft speed: Zero.
Out put shaft gear speed: Zero.
Input shaft gear: 2Ni.
Wheel ends speed: 2N2.
Hence, as soon as the brakes get applied, 100% differential action will get achieved
for that particular time and 0% differential action will be achieved when brake will
get disengaged.
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Braking force (Load) can be applied to the axle wheel ends with the help of dynamometers.
The foregoing description is a specific embodiment of the prevent invention. It should be appreciated that this embodiment is describe for this purpose of illustration only and that numerous alteration and modification may be practiced by those skill in the art without departing from the spirit and scope of the invention. It is intended that all such modification and alteration included in so far as they come within the scope of the invention as clamed the equivalent thereof.
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WE CLAIM
1. A test set up for testing of interaxle differential assembly with the help of brake
dynamometer on bench comprising
main motor adapted to give input speed to the interaxle differential assembly through transmission means;
said interaxle differential assembly is configured for mounting input shaft and output shafts;
at least two dynamometers are connected to the interaxle differential assembly wheel ends to provide torque / load;
at least one brake drum configured to be coupled on said output shaft;
at least one brake assembly configured for applying brake pressure on said brake drum;
at least one PLC (Programmable Logic Controller) for actuating solenoid valve of said brake assembly;
at least two step down gear box configured to be mounted on each of the wheel end sides between said dynamometer and said wheel end facilitated for controlling dynamometer speed;
facilitated for testing strength of interaxle differential gears of interaxle differential assembly.
2. The test set up as claimed in claim 1, wherein said solenoid valve is a pneumatic solenoid valve.
3. The test set up as claimed in claim 1, wherein said interaxle differential assembly is the first rear interaxle differential assembly.
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4. The test set up as claimed in claim 1, wherein said brake assembly is a hydraulically actuated brake assembly and is grounded with proper alignment with said brake drum.
5. The test set up as claimed in claim 1, wherein said brake assembly is actuated by actuating means like brake pedal.
6. The test set up as claimed in claim 1, wherein step down gear box is used between main motor and said interaxle differential assembly for controlling motor speed to required speed.
7. A test set up for testing of interaxle differential assembly with the help of brake dynamometer substantially as herein above described and as illustrated in accompanying drawings