A LEAF SPRI NG PAD WHI CH PROVI DES LI NEAR CONTACT

Technical Field of the I nvention

The invention subject to the application is related to a spring leaf pad, which is used to couple the spring leaf and the bushing when the wheels of vehicles, which carry cargo and/or passengers, particularly in which air suspension and mechanic parts are used, carry out motion in directions opposite to each other (perpendicular direction) ; and which provides linear contact related to increase the contact surface of the interface part ( lead spring pad) that performs force transmission between the bushing and the leaf spring.

State of the Art related to the I nvention ( Prior Art)

The invention subject to the application forms high tension/forces on the spring leaf pad which is the intermediate coupling part that provides coupling of the bushing and the leaf spring part parallel with the increase of the strokes when one wheel is carrying out a descending motion and the other wheel is carrying out an ascending motion during the movement of the right and left wheels in opposite directions to each other, in vehicles that are used to carry cargo and passengers.

New parts are being tried on interface parts in order to decrease the tension levels between the bushing and the leaf spring parts, to reduce tension force and to be able to transfer this force onto wider surfaces. However as the bushings are half pressed by means of hot shaping methods and are then coupled together the surface cannot be provided at the planar level required on surfaces where the bushings having square and rectangular sections form said surfaces. These conditions cause the spring leaf pad to have contact or contacts on points instead of surface contact . Force transmission is provided from only one point due to point contact on the spring leaf pad. As these two mechanically sensitive parts that provide force transm ission of the bushing and the leaf spring parts to each other are coupled with each other from only a point ; this causes the system to be weak in terms of mechanic and performance criteria. The point contact brings excessive loads onto the sources that enable to fix the spring leaf pad to the bushing and at the same time causes high tensions in these areas. The invention subject to the application elim inates the weaknesses at the points of power transmission as it converts point contact into linear contact by ensuring that load transfer is distributed from two different surfaces that are in contact with each other.

I n the cases where high values of force is applied by the strokes between the right and left wheels in opposite directions (perpendicular direction) in vehicles which carry cargo and/or passengers, particularly in air suspension vehicles, serious problems may occur such as damages, abrasions, deformations, and cracks in the spring leaf pad welding areas which could also be observed in test applications which contained low track distances.

The spring lead pad interface part which connects the bushing and the leaf spring part to each other which are known in the state of the art provide point contact between the surfaces but it provides this contact from only one point. The interface part connection area is not formed of a point but from a linear surface according to the invention subject to the application . As a result of the tension surface to which force is applied being increased, the cracks, damages or deformations that may occur at the point of contact are prevented.

By means of the novel spring leaf pad invention which provides linear contact , the lifespan of the product is increased by tenfold, and abrasions, scratches and damages are reduced.

It is critically important in terms of the life span of the vehicle to minimize the interaction of the main parts; which primarily affect the durability parameters of vehicles and which significantly contribute to the mobility of vehicles that carry cargo and/or passengers and particularly air suspension vehicles. The abrasion of the bushing and leaf spring parts which have essential effect on the mobility of the vehicle, increases passenger and driver safety risks. These depreciations are minim ized by means of the invention subject to the application and the security risks are reduced.

Brief Description of the I nvention and its Aims

The interface part ; which absorbs the tension force between the bushing and the leaf spring when the wheels of the vehicles subject the invention, carrying cargo and/or passengers, particularly vehicles where air suspension and mechanic parts are used, carry out a motion in opposite directions to each other; is fitted onto the bushing from the bushing surface in present applications and is then welded onto the bushing by welding to the bushing from the sides. This method is thought to be risk free when theoretical aspects are taken into consideration , however when said method is evaluated together with application aspects, and when aspects which directly affect production techniques such as bushing surface production method errors, mechanic part geometrical tolerances, are taken into consideration it can be observed that cracks/damages occur on the coupling surfaces of the two parts that are connected to each other. The weaknesses, abrasions between the bushing parts and the connection surfaces that arise as surface contact cannot be provided in reality, where theoretically surface contact needs to be provided in present applications, are prevented by means of the invention subject to the application, by form ing a linear interface between the two parts.

Linear contact continuity is provided at the radius regions where it is probable for the bushing parts to provide contact and as a result the characteristic of being able to provide load transfer over parts has been discovered. Point connection and force transmission from a single point is eliminated by means of the spring leaf pad which provides linear transfer along the region .

The following has been obtained by means of the spring leaf pad which provides linear contact ;

• Force transmission is distributed homogenously.

• Risks that cause mechanic wear are elim inated.

• The negative effects that are transferred to the system due to errors within the tolerance limits, during the production and application of bushing surfaces are minim ized.

• Total mechanical risks which are affected primarily by interface parts are reduced.

• As force transmission is carried out from corners that are orthogonal the system is enabled to become resistant against torsion stress.

• By means of the connection type created by this design, the high forces transferred onto the connection welding are decreased and as a result the tension created in said regions are minim ized and the damage risks at the connection regions are eliminated.

Definition of the aspects/ sect ions/ parts that form the invention

The parts/sections/aspects that have been shown in the figures that have been prepared in order to further describe the spring leaf pad which provides linear contact and which has been developed by means of the present invention have each been numbered and the references of each number has been listed below. 1 . Spring leaf pad (prior art)

2. Bushing primary surface

3. Bushing

4. Essential contact points (prior art)

5. Contact region

6. Leaf spring valve seat

7. Spring leaf pad

Definitions of the figures illustrating the invention

The figures that have been prepared in order to further illustrate the spring leaf pad which provides linear contact developed according to the present invention are described below.

Figure 1 - the view of the (prior) spring leaf pad valve seat providing point contact.

Figure 2 - the detail view of the (prior) spring leaf pad valve seat providing point contact Figure 3 -the view of the (Novel) spring leaf pad valve seat providing linear contact

Detailed description of the I nvention

The invention subject to the application is related to a spring leaf pad (7) that has been developed to distribute large forces properly, to reduce the risks that may occur and to provide linear contact, and to enable coupling of the bushing (3) and the leaf spring part that is parallel to the increase of the strokes when one wheel is carrying out a descending motion and the other wheel is carrying out an ascending motion during the movement (at a perpendicular direction) of the right and left wheels in opposite directions to each other in vehicles that are used to carry cargo and passengers.

Surface connection at the contact region between the spring leaf pad ( 1 ) and the bushing (3) cannot be provided as the essential surface (2) of the bushing is not planar (shown in Figure 1 ) when the bushing (3) and the spring leaf pad (1 ) are placed on top of each other in the known state of the art. The contact between the bushing (3) and the spring leaf pad ( 1 ) is provided as point contact in reality. The essential contact points (4) have been shown in Figure 1 and Figure 2. It has also been observed that the contact between the spring leaf pad ( 1 ) and the bushing (3) is point contact, as a result of the tests that were carried out. The invention has been developed such that linear contact is provided in all cases by taking into consideration the production tolerances of the bushing and the regions (5) where the spring leaf pad (7) contact the bushing, in order to provide more contact by means of the spring leaf pad (7) at the radius contact region (5) of the bushing ( Figure 3) . As the system is not dependent on the contact between the bottom surface of the spring leaf pad (7) and the top surface of the bushing (3) , the undulating surfaces that occur on the surface of the bushing (3) during the production stage of said bushing (3) , does not affect the linear contact (5) between the bushing (3) and the spring leaf pad (7) .

The undulating top surface of the bushing (3) occurs due to the production stage of the bushing. The most smooth surface of the bushing (3) is the radius regions. As a result the contact region (5) where the spring leaf pad (7) contacts the bushing (3) has been designed to provide linear contact. Therefore linear contact is provided between the bushing (3) and the spring leaf pad (7) along the contact region (5) .

The contact region (5) has a geometrical structure which provides linear contact with the bushing (3) .

The main aim of the spring leaf pad subject to the invention can be summarized as follows;

• .Establishing a linear contact spring leaf pad (7) surface that provides the force transmission between the bushing (3) and the leaf spring valve seat (6) at the best possible ratio,

• Providing linear contact along a linear line by means of the linear spring leaf pad (7) application,

• Reducing the errors of the bushing (3) and the spring leaf pad (7) parts during production applications that may create malfunction in the system however are within the tolerance limits by means of linear application and contact,

• Providing planar surface and geometric continuity by means of linear application ,

• Reducing risks, wear, and damages that may occur on the leaf spring (6) parts and at the connecting welding regions of the spring leaf pad (7) and the bushing (3) subject to the application developed by means of the linear application, of the spring leaf pad ( 1 ) application, providing point contact.