Field of the invention

The present invention belongs to the field of mechanical engineering, more precisely to the field of forestry trailers for transporting different heavy loads, in particular harvested logs. The invention relates to a mechanical construction of protection of spikes (handles) of the forestry trailer.

The technical problem

The technical problem, which is solved by the present invention, is construction of a safety mechanism for spikes (handles) of a forestry trailer for transporting heavy loads, such as logs from a forest. The construction should enable rotation of spikes of an empty or full trailer around their axis for a pre-defined angle. The problem is to limit the rotation into left or right in freely inserted spikes into holders, which are usually installed in pairs coaxially on longitudinal sides of the trailer. During transport of empty trailers, the spikes can freely move left in rights with respect to movement of the whole trailer. Sometimes the spikes reach such positions that they have to be manually put into their original place. The shape and the weight of spikes pose a problem to the driver of the trailer. If the movement of spikes around the axis of the holder is limited for a particular angle, this may result in deformation or breaking of the holder during loading of logs or in case of an obstacle. When larger forces are present, even the framework of the trailer can be damaged. It is therefore required to predict that the protective or restrictive part of the spike may be broken.

In addition to preventing complete rotation of the spikes, the constructional solution of the protection (guards) should also enable protection against detachment of spikes from their carriers (holders). State of the art

A solution by Austrian company STEPA is known, which for limiting the rotational movement of spikes inside holders uses a screw, installed in the bottom part of the spike under the lower edge of a cut holder. The screw is installed through the spike, so that the head of the screw is on one side and a bolt is screwed on the other side.

The majority of spikes of forestry trailers do not have any additional protection or devices for limiting rotation of spikes inside holders.

Description of the solution of the technical problem

The essence of the forestry trailer with the safety mechanism of spikes according to the invention is that it is usually equipped with one or more pairs of parallel spikes installed in holders, which have their bottom edges preferably obliquely cut or have different oval and/or rectangular cuttings (cut-outs). The spikes are in their bottom part provided with screws, which are mounted into one side (wall) of the spike, in order to limit rotational movement of each spike inside its cylindrical holder. For a reliable function of the safety screw, the geometry of the bottom edge of the holder and the location of the screw are important. In case of exceeded force of loaded logs to one or more spikes, for example when spike hits an obstacle, a pre-defined shear force of the holder edge to the nut of the screw will cause the screw to break, which will prevent damage of carrier elements of the trailer.

The forestry trailer with the safety mechanism of spikes will be described in further detail based on figures, which show:

Figure 1 the forestry trailer with the safety mechanism of spikes;

Figure 2 the holder and the spike according to embodiment I;

Figure 3 the holder and the spike according to embodiment II. The forestry trailer with the safety mechanism of spikes is equipped with one or more pairs of parallel spikes installed in holders 2, 2' on longitudinal parts 1a and 1b of a chassis 1. The holders 2 and 2' have their bottom edges cut in such a way that their edges have an approximate shape of a circle, preferably oval or cut-outs having any other shape. The spikes 3 and 3' are provided in their bottom part with screws 4 in one side (wall) of the spike, which enables limitation of rotational movement of each spike inside its cylindrical holder.

The forestry trailer with the safety mechanism of spikes has pairs of holders 2 and 2' welded to longitudinal parts 1a and 1 b. Pairs of spikes 3 and 3' are installed into holders 2 and 2'. Spike 3 is shaped so that the bottom part is a short cylinder, the axis of which is installed in the axis of the holder 2. The longitudinal parts 1a and 1b of the chassis 1 may have installed and/or welded a different number of holders 2 and 2', which usually depends on the size of the forestry trailer.

When the spike 3 is installed in the holder 2, a screw 4 with a nut or any other protective or mechanical element is mounted into a pre-prepared hole in the bottom part of the spike 3. In the same way, the spike 3' is installed in the holder 2', so that the screw 4 with a nut or any other protective or mechanical element is installed in a pre-prepared hole in the bottom part of the spike 3'. The shape of the bottom edge 21 of the holder 2 and the screw 4 in the spike 3 define the maximum angle of rotation around the vertical axis of the holder to the left or right direction.

The forestry trailer with the safety mechanism of spikes may have holders 2 and 2', which have in addition to the oval bottom edge also a cut-out of a suitable shape, preferably rectangular or trapezium shape. The screw 4 with the nut may be any protective (safety) or mechanical element. The position of the screw 4 on the spike 3 defines the maximum angle of rotation around the vertical axis of the holder 2. The forestry trailer with a safety mechanism of spikes has such a bottom edge or cut-out of the holder 2, which cuts the nut of the screw 4 in case of overload on the spike 3. Movement of the spike 3 is thus enabled. The same is also possible on the other side, when in case of an overloaded spike 3' the bottom edge or the cut-out on the holder 2' cuts the nut of the screw 4 and enables movement of the spike 3'.

The forestry trailer with the safety mechanism of spikes according to embodiment I has the longitudinal parts of the chassis provided with pairs of holders 22, which are attached by welding, wherein the preferred position of the holders is perpendicular to the longitudinal axis of the chassis. Into the pairs of holder 22 pairs of spikes 32 are installed. The spike 32 is shaped in the same way as the spike 3 from figure 1. The spike on the other side of the chassis is a mirror image of the spike 32. According to embodiment I the bottom edge 221 of the holder 22 is shaped so that the bottom part is cut at an angle and has a shape of an ellipse with the open part directed outwards.

The forestry trailer with the safety mechanism of spikes according to embodiment II has the longitudinal parts of the chassis provided with pairs of holders 23, which are attached by welding, wherein the preferred position of the holders is perpendicular to the longitudinal axis of the chassis. Into the pairs of holder 23 pairs of spikes 33 are installed. The spike 33 is shaped in the same way as the spike 3 from figure 1. The spike on the other side of the chassis is a mirror image of the spike 33. According to embodiment II the holder 23 is shaped so that the cut-out has a suitable shape, which still allows the safety function in case of overloads and at the same time allows rotation of the spike for a pre-defined angle. Depending on the rotational movement of the spike 33, the screw 4 will be on the left or right side.

The characteristic of the present invention is in that the design of the holder and the bottom part of the spike equipped with a screw or any other safety or mechanical element for limiting rotational movement of the spike and protecting the spike against falling out of the holder, enables protection of basic carrying elements of the forestry trailer such as the chassis, holders and spikes. The constructional design of the holder, the spike and the screw is such that it enables rotational movement of the spike inside the holder for a pre-defined angle and prevents detachment of the spike from the holder.