The intermediate steering shaft is an assembly of parts positioned between the steering column and the steering box, which has as function the transmission of the rotation movement exercised by the driver on the steering wheel, which makes the front wheels of the vehicle to be steered, allowing them to change the direction course.

The intermediate steering shaft mounted on the steering box and on the steering shaft through extreme end yokes, whose internal splines couple to the spline of the fitting of those devices with a specified force, guaranteeing the torque transmission.

Besides the previously described function of driveability, the intermediate steering shaft must also allow the tilt movement of the vehicle's cabin during the maintenance period, moment in which this needs to be significantly distended.

In order to solve this problem have been adopted trivial solutions that are restricted to the serial elongation of the splined bar of the internal end yoke with the proportional elongation of the intermediate splined sleeve. Through this logical and obvious reasoning one obtains a long course of the intermediate steering shaft.

However, such solution generates a greater consumption of material, longer time spending in the execution of the splines, besides a substantial increment of weight in the intermediate steering shaft assembly.

Another problem, which is more serious and of difficult solution, is the fact that some vehicles has a reduced space between the steering column and the steering box to install the intermediate steering shaft, which makes the previous presented solution non feasible, once it presents a large length to obtain the long course demanded.

The objective of the present invention is an new concept

developed for the intermediate steering shaft that adopts a third segment of axial sliding, allowing an addition distention of the shaft in relation to the work stage. This third segment has its operation restricted to the vehicle's maintenance activities, being put into operation only during the tilt movement of the vehicle's cabin. A splined bushing with an internal spline and an extension tube forms the third element. The splined bushing slides over the splined bar of the internal end yoke. The extension tube involves externally the mentioned splined bushing in one of its ends, and on the opposite end it is supported by the slip yoke, that moves over the external surface of the slip yoke.

The improvement on the intermediate steering shaft, proposed by the invention, results in the following advantages over other known devices: -it enables the distention of the intermediate steering shaft beyond the normal sliding length, comprise by the bar and sleeve splines. This is obtained through the addition of the third parallel segment, which enables the axial sliding of a second segment, in sequence to the work stage. With this conception, it is granted to the intermediate shaft a large capability of distension, even when installed in vehicles with little space between the steering column and the steering box, obtaining a larger tilt course of the cabin for the vehicle's maintenance ; -the addition of the third parallel segment with exclusive operation for the function of the vehicle's cabin tilt movement, does not interfere in the level of radial looseness of the intermediate shaft, as it does not participate of the torque transmission system; -the third parallel segment is of less responsibility, for it only operates when the intermediate steering shaft is distended with the vehicle not transiting, which allows its manufacture with less severe dimensional tolerances, greatly facilitating the production process.

-it results a smaller area of components spline responsible for the torque transmission, decreasing the material volume and the machining time, and it also reduces significantly the weight of the column assembly.

In order to help to understand the improvement developed in the intermediate steering shaft, object of the present invention, the same will be

described in details, with basis on the following drawings: Figure 1-perspective of the intermediate steering shaft, partially in sectional drawing, in the position of work and retracted; Figure 2-perspective of the intermediate steering shaft, partially in sectional drawing, in the position of work and distended; Figure 3-perspective of the intermediate steering shaft, partially in sectional drawing, in the vehicle's maintenance position and totally distended; Figure 4-perspective of one of the intermediate steering shaft's ends.

Figures 1 and 2 illustrate, respectively, the minimum and maximum distensions of the intermediate steering shaft, without the third segment having been put into operation. The shaft comprises external end yokes (1), meant for coupling on the splined ends of the steering column and the steering box, where the end yokes are mounted (2). On one of the journal crosses (2) is mounted an internal end yoke (3) that is fitted in a spline bar (4), while on the opposite journal cross is mounted the slip yoke (6). Over the splined bar (4) slides the extension tube (5), which, on its turn, is connected to the slip yoke (6).

The operation of the third segment is seen in Figure 3 and starts after the work stage distension is finished, represented in Figure 2. This segment comprises an splined bushing (7), that slides over the splined bar (4), over the bushing is properly fixed an extension tube (8), which opposite end has windows (9) where there are mounted the sliding guides (10). The sliding guides (10) moves axially on level surfaces (11) executed on diametrically opposite positions on the external surface of the slip yoke's (6) tube (5). So that the sliding guides (10) remains inside of the windows (9) of the extension tube (8) it is mounted an external cover (12) over them.

The torque transmission, during the first stage of the distension of the intermediate steering shaft, to occur only between the splines of the splined bar (4) and the slip yoke (5). An automatic device keeps the third segment in place. Such device, partially illustrated in details in Figure 4, comprises a locking ring (15) that is fixed on the slip yoke (6) through a detent spring (16) that fits into a specific housing. On the ring (15) opposite end is a

locking spring (14) positioned in a peripheral slot, whose laterals are totally hole. In this way, the spring (14), that has the lateral branches straight, crosses the ring's thickness (15), becoming free to penetrate in the peripheral slot (13) executed on the guides'cover (12). So, the guides'cover (12) is captured under the ring (15) by the action of the locking string laterals (14).

As previously seen, the third sliding segment has no function during the vehicle's normal movement, as in this situation the torque is transmitted from one end yoke (1) to the other, through the external spline of the splined bar (4) and the internal spline of the slip yoke (5). In this situation the addition course for tilt movement is not required, and the third segment must remain in its housing over the slip yoke (6), by action of the locking spring (14), avoiding unnecessary wear to the system. Whenever necessary to execute the tilt movement of the vehicle's cabin, the locking spring (14) is forced to expand its lateral branches, allowing the disconnection between the extension tube (12) and the sequence ring (15) fixed on the slip yoke (6).

When the vehicle's cabin is tilted, the splined bar (4) is moved away from the slip yoke (5), as illustrated in Figure 3, the intermediate steering shaft still remaining mounted by the action of the third segment. In this situation, the splined bushing (7) remains coupled on the splined bar (4) and the sliding guides (10) run to the ends of the level surfaces (11) of the slip yoke (5). The guarantee of the relative angular position between the spline bar (4) and the slip yoke (5), avoiding a wrong regulation of the wheel's position. It is also guaranteed the re-coupling of the spline bar (4) on the slip yoke (5), at the moment when the cabin returns to its normal position.

In order to avoid the complete disengagement of the intermediate steering shaft are foreseen, optionally, the following mediums: -execution, through a pin insertion between two tooth, of a bumper on the free end of the splined bar (4), after the assembly of the third segment, in this way being blocked its exit; so that this bumper does not impede the normal sliding of the slip yoke (5), this should have a double gap in its spline that can receive the bumper without the separation of the splined bar (4) being hindered ; -the sliding guide (10) do not separate from the external surface of the slip yoke

(5) because their level surfaces (11) are interrupted on the slip yoke's (5) free end; in this way, the mounting of the guides (10) on the windows (9) of the extension tube (8) and posterior positioning on the slip yoke's (11) level surface grant a cohesion with axial movement freedom to the assembly along the length of the level surfaces (11).