FORM 2
THE PATENTS ACT 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. TITLE OF THE INVENTION; "Locking Feature in Tensioner"
2. APPLICANT:
i
(a) Name: ADVIK HI-TECH PVT. LTD.
(b) Nationality: Indian
(c) Address: Gate No. 357/99,
Chakan Talegaon Road, Village Kharabwadi, Chakan, Tal. Khed, Pune - 410501 Maharashtra, India

Field of Invention
The present invention relates to a tensioner that imparts a predetermined tensile force to a force transmitting member such as a chain or timing belt that drives a camshaft of an engine mounted in a vehicle for e.g. four wheeler automobile or a two wheeled vehicle.
Background of Invention
A tensioner works to maintain constant tension of a timing chain or timing belt used for an engine of an automobile by pushing the timing chain or belt with a predetermined force if the chain or timing belt becomes loose or slack.
A conventional tensioner consists of a body, screw, nut. retainer, O-ring. Stopper, cap. spring and circlip. Tensioner body has cylindrical portions extending on both sides from the flange. Also tensioner body has slit extending from the flange to the cylindrical portion. Screw has a slit formed in its head. Spring used has its one end placed in the slit of the screw and other end placed in the slit provided in the body. Screw is threadedly engaged with the nut. Stopper is used to provide rotary motion to the screw. Rotary motion of the screw forces the spring to rotate as well. Thereby elastic energy is stored in the spring. Upon removal of the stopper from the

screw, the stored elastic energy in the spring rotates the screw. Retainer is placed on the body of the tensioner. The retainer acts as a guide for motion of the nut. Since the screw is threadedly engaged with the nut. Rotary motion of the screw is converted into linear motion of the nut as the retainer prevents the nut from rotating.
Hence, the problem existing with such tensioners is that the retainer does not have an adequate provision to restrict the linear movement of the tensioner when it moved by the screw.
Therefore, it is essentially required to provide a locking feature in tensioner which overcomes the aforesaid drawbacks and shortcomings of the prior arts.
Object of Invention
The main object of the present invention is to provide a locking feature in tensioner.
Another object of the present invention is to provide a locking feature in tensioner which overcomes drawbacks and shortcomings of prior art.
Summary of Invention
A tensioner according to present invention comprises a body adapted to mount in proximity of transmission media; a nut adapted to slide-ably project out from the opening of the body: a screw adapted to

guide the nut which is configured to rotate and deliver axial motion to nut; a spring acting between the body and screw to urge nut in direction to project out from opening, a stopper to removably insert in slit of screw to lock the screw in inoperative condition; and a retainer with locking means, The retainer, made up of steel or sintered materials, haivng dome type or flat type inside of the retainer being configured to act as a locking means. Further, said nut is configured to move inside retainer between arresting position and the flange of the screw.
Brief description of drawings
Various other objects, features and many of the attendant advantages of the present invention will be understood by reference to the following detailed description of the preferred embodiment of the present invention when considered in connection with the accompanying drawings, in which:
Fig. 1 illustrates a cross sectional view of the tensioner according to the present invention.
Fig. 2 illustrates an isometric view of the across flat portion of the nut according to the present invention.
Fig. 3 illustrates an isometric view of the retainer according to the present invention.
Fig. 4 illustrates a bottom view of the retainer according to the present invention.

Detailed description of Invention
The nature of the invention and the manner in which it works is clearly described in the complete specification. The invention has various embodiments and they are clearly described in the following pages of the complete specification. Before explaining the present invention, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and nut of limitation.
Now referring to Fig.l, a tensioner according to the present invention comprises a screw (1), a nut (2). A body (3), a spring (4), a retainer with locking feature (5), washer (6), a spacer (7), a circlip (8), a cap (9), a plug (10) and a stopper (11). The screw (1) provided has a slit formed in its head. Said screw (1) has external threads which engages with the internal threads of the nut (2). One end of the spring (4) is engaged in the slit provide in the screw (1) while other end of the spring (4) is engaged in the slot provided in the body (3). The washer (6) is placed above the end face of the screw (1). The cap (9) is fitted on the nut (2) by crimping. The plug (10) is placed in the groove provided in the body (3). The circlip (8) holds the retainer (5) placed on the body (3).
As shown in Fig.2, the across flat portion (12) being extended from the top portion of the nut (2) to the bottom of the nut (2). The base of the across flat portion (12) of the nut (2) has a projection (13) extending radially outward from the surface of the nut (2).

As shown in Fig.3, the retainer (5), made up of steel, is a projected member having both ends are open. The retainer (5) includes at least two number of lugs (14). The lugs (14) provided on the retainer (5) fits in the slots provided on the retainer (5). The lugs (14) provided on the retainer (5) being projected radially outward from the retainer (5). The retainer (5) has a dome type or flat type projection (15) inside of the retainer surface. Said projection (15) provided on the inside of the retainer (5) surface is primarily responsible to restrict the linear motion of the nut (2) as per the required stroke.
Further referring to Fig.2, said nut (2) being provided in the tensioner has an across flat portion (12). The length of the across flat portion (12) depends upon the stroke required. Across flat portion (12) provided on the nut (2) has a projection at its base. The projection at the base of the across flat portion (12) is perpendicular to the across flat portion (12).
As depicted in Fig. 4 the projections (15) of the retainer (5) limit the linear motion of the nut (2) by engaging with the projections (13) provided at the base of the nut (2).
The present invention has been described with reference to the specific embodiment, which is merely illustrative and nut intended to limit the scope of the present invention, which is defined in the following claims of the complete specification.

We claim,
1. A tensioner for an endless driving elements, comprising:
a body (3) adapted to mount in proximity of transmission media;
a nut (2) adapted to slide-ably project out from the opening of the body (3):
a screw (1) adapted to guide the nut (2) which is configured to rotate and deliver axial motion to nut (2);
a spring (4) acting between the body (3) and the screw (1) to urge the nut (2) in a direction to project out from the opening.
a stopper (11) adapted to removably inset in the slit formed in the screw (1) to lock the screw (1) in an inoperative condition; and
a retainer (5) provided with a locking means;
characterized in that,
the nut (2) adapted to move inside the retainer (5) between an arresting position provided on the retainer (5) and the flange of the screw (1) to arrest the movement of said nut (2).
2. The tensioner as claimed in claim 1, wherein the retainer (5) provided with locking means is a dome type or flat type being made up of steel or sintered materials.
3. The tensioner as claimed in claim 1, wherein the retainer (5) has projections extending from the inside of the retainer (5) that is configured to act as locking means.

4. The tensioner as claimed in claim 1, wherein the nut (2) is made of the mild carbon steel or low carbon steel.
5. The tensioner as claimed in claim 1, wherein the nut (2) has an across flat portion (12).
6. The tensioner as claimed in claim 1, wherein the nut (2) has a projection at the base of the across flat portion (12).