This invention relates to & gear box assembly for use in an epicyclic gear reduction starter motor for automotive applications.
The gear box assembly proposed herein is intended to protect the gear elements from damage during overload conditions occurring while cranking the engine.
Known gear boxes m epicyclic gear reduction starters have attempted the use of mechanisms in the nature of friction plate clutches providing slippage during overload conditions, for avoiding damage to gear elements. However, such mechanisms have been found to be cumbersome in terms of sp{u;e occupied, weight end dimensions.
This invention, on the other hand, achieves the desired result, is cost effective, simple in construction, adapted for use in conventional epicyclic gear boxes and suited to high vohime automated assembly lines.
Various other features of this invention will be apparent from the following dedcription.
The gear box assembly for use in an epicyclic gear reduction starter motor for automotive applications, according to th is invention, is provided with a housing accommodating gear elements, such as, planetary gears

The characteristic feature of this invention is that a circular metal strip member T is snugly located between the internal gear- annulus A and the housing H. The strip member T has alternate ridges R and grooves G on its periphery, which remain m close contact with the internal gear-annulus A.
During normal conditions the strip member holds the internal gear-annulus A and does not allow it tot slip. It is only when under conditions of overload on the starter, that is, when the torque on the starter exceeds a predetermmed value, greater than the normal cranking torque, the strip member allows the internal gear-annuhis A to slip against the said ridges R and grooves G, thus avoiding damage to the gear elements, while cranking the engine.
The strip member can be made in two forms: one where the said member has its ends free; the other when the said member is endless.
One of several materials the strip member may be made of, is alloy steel
From the foregomg, it will be appreciated that varions other embodiments of this invention are possible without departing from the scope and ambit thereof

We Claim:
1 A gem- box assembly for use in an epicyclic gear redaction starter motor for automotive applications provided with a housing accommodating gear elements, such as, planetary gears surrounding, and meshing with, a sun gear; an internal gear-annnlus meshing with the planetary gears, characterised in that a circular flexible metal strip member is snugly located between the internal gear- annuhis and the housing, the strip member having alternate ridges and grooves on its periphery in close contact with the internal gear-annnlus, whereby under conditions of overload, when the torque on the starter exceeds a predetermined value, greater than the normal cranking torque, the strip member allows the internal gear-annulus to slip against the said ridges and grooves, thus avoiding damage to the gear elements and also ensuring concentricity of the mtemal gear annuhis, planetary gears and sun gear.
2.A gear box assembly as claimed in Claim 1 wherein the strip member is made of alloy steel.
3.A gear box assembly as claimed in Claim 1 or Claim 2 wherein the strip member has two free ends.
4.A gear box assembly as claimed in Claim 1 or Claim 2 wherein the strip member is endless.

S.A gear box assembly for use in an epicyclical gear reduction
starter motor for automotive applications, substantially as herein described with reference to, aid as illustrated in, the accompanying drawings.
Dated this the 4th day of November 2003