FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
An endurance testing machine for springs
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, WorJi, Mumbai - 400 030, Maharashtra, India, an Indian Company
INVENTORS
Ghosh Baidyanath, of Crompton Greaves Limited, IPR Cell & Technical Information Centre (TIC), C G Global R&D, Kanjurmarg (East), Mumbai 400 042, Maharashtra, India, an Indian National
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to an endurance testing machine for testing springs.
BACKGROUND OF THE INVENTION
This invention is associated with spring endurance testing machine used for testing spring fatigue. Failures occurring in springs can be attributed broadly due to process failures and raw material failures. Process failures occur due to faulty manufacturing process employed in manufacturing springs and raw material failures occur due to improper raw materials used in the manufacturing of springs. Failures occurring during the lifetime of a spring can either manifest in the form of a deformity in the shape and size of the spring or spring breakage.
An endurance testing machine is developed to emulate the stress conditions that occur over an extended period of time by repeated operations of expansion and contraction on the spring. A selected lot of springs from every manufactured lot can undergo endurance testing to check for process and raw material failures and required quality compliance. The manufactured lot can be passed of failed depending upon the result of operations on the select lot springs.
OBJECTS OF THE INVENTION
An object of the invention is to provide an endurance testing machine to test for process and raw material failures in springs.

DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a testing device for testing the endurance of a spring. The device comprises of a stationary plate mounted on a base and having holding means for holding one end of the spring to be tested and a movable top disposed above the stationary plate in spaced apart relationship with the stationary plate and having holding means for holding the other end of the spring to be tested, the movable plate being disposed for guided up and down movement with respect to the stationary plate and a drive means for moving the movable plate up and down and a counter means for counting each cycle of up and down movement of the movable plate and a linear scale vertically mounted on the base and an indicator fixed to the movable plate and positioned against the calibrations on the linear scale.
The following is a detailed description of the invention with reference to the accompanying drawings, in which:
Figure 1 is an isometric view of the testing device according to invention.
Figure 2 is a front view of the testing device according to the invention.
Figure 3 is a side view of the testing device according to the invention.
The testing device for testing endurance of a spring as illustrated in Figures 1 to 3 of the accompanying drawings comprises of a stationary plate 1 and a moveable plate 2 between which a spring to be tested is disposed by holding them between hooks 12, provided on the stationary plate 1 and the moveable plate 2. The stationary plate 1 is

mounted on a base 19. Stationary plate 1 is provided a pair of inner members 5. The moveable plate 2 is provided with a pair of outer members 6. The moveable plate 2 is mounted with its outer members 6 is disposed over the inner members 5 and is provided a guided movement on the inner members 5. The moveable plate 2 is attached to a circular flange 7 by means of an adjustable stroke rod 8. Adjustable stroke rod 8 is eccentrically pivoted on the circular flange 7 and is provided lateral support by means of a position retainer 10. Adjustable stroke rod 8 can be adjustably mounted on the position retainer 10 to suit springs of different sizes. Rotation movement of the circular flange 7 is performed by an electric motor 13. The electric motor 13 is mounted over a base 20 which is higher than base 19 and accommodates the height between which the moveable plate 2 and stationary plate 1 are disposed. As the adjustable rod 8 is pivoted eccentrically, it is subjected to an up and down movement, and this movement is transmitted to the movement plate 2. A lateral movement of the adjustable rod 8 is restricted by means of a position retainer 14 on the circular flange 7. Position retainer 14 comprises of an oblong member 15 securely fixed on the circular flange 7 by means of a nut and bolt arrangement. The adjustable rod 8 has a threaded end which can be tightened with the oblong member 15 by means of the nut and bolt to get a desired length of the adjustable rod 8 for springs of different sizes. The up-down movement of the moveable plate 2 exerts an expansion and compression of the spring disposed between the moveable plate 2 and the stationary plate 1. A counter 16 placed adjacent to the stationary plate 1 counts the number of times expansions and compressions are exerted on the spring. The counter 16 receives a hit from a rod 17 disposed down from the moveable plate 2. Counter 16 increments the current count for every downward traversal of the moveable plate 2. A spring is subjected to recommended/pre-defined number of compression and

expansions. A linear scale 18 is disposed between the moveable plate 2 and stationary plate 1 to measure the lengths of the spring before an.d after the compression and expansion is performed on the spring. The continuous compression and expansion may cause the spring to get elongated and at times result in spring breakage. Linear scale 18 is used to check if the elongation of the spring is within tolerable limits as defined by the spring manufacturer. Continuous expansion and compression can also cause a deformation in the spring (permanence set) and this indicates a process related failure in the manufacturing of the spring. A spring breakage can indicate improper proportion and/or quality of raw materials used in the manufacturing of springs.
Variations in the construction and configuration of the invention for achieving the above objectives are obvious to those skilled in the art and such variations are to be construed and understood to be within the scope of the invention.

We claim:
1. A testing device for testing the endurance of a spring, the device comprising:
a stationary plate mounted on a base and having holding means for holding one end
of the spring to be tested ;and
a movable plate disposed above the stationary plate in spaced apart relationship with
the stationary plate and having holding means for holding the other end of the spring
to be tested, the movable plate being disposed for guided up and down movement
with respect to the stationary plate; and
a drive means for moving the movable plate up and down ; and
a counter means for counting each cycle of up and down movement of the movable
plate ; and
a linear scale vertically mounted on the base and an indicator fixed to the movable
plate and positioned against the calibrations on the linear scale.
2. The testing device as claimed in claim 1, wherein the holding means of each of the stationary plate and movable plate is a hook.
3. The testing device as claimed in claim 1 or 2, wherein the stationary comprises a pair of spaced apart upright inner members and the movable plate comprises a pair of equally spaced apart outer members disposed over the inner members and the movable plate being guided on the inner members during the up and down movement thereof.
4. The testing device as claimed in any one of claims 1 to 3, wherein the drive

means comprises a motor mounted on a support frame for rotation about a horizontal axis, a circular flange mounted at the outer end of the motor shaft and a drive rod one end of which is eccentrically pivoted to the flange and the other end of which is pivoted to the movable plate, the guide rod being retained in position in a position retainer.
5. The testing machine as claimed in claim 4, wherein the position retainer comprises an oblong member fitted on the flange and having a channel along the outer surface thereof, the drive rod being located in the channel with its said one end pivoted to the oblong member.
6. The device as claimed in any one of claims 1 to 5, wherein the counter means comprises a mechanical counter mounted on the base and an actuator fixed to the movable plate adapted to actuate the mechanical counter.