Crawler vehicles normally comprise a motor connected to a transmission device by means of a main clutch. The transmission device rotates a right shaft and a left shaft, connected respectively to a right drive sprocket and a left drive sprocket, each of which is arranged for moving a corresponding track. A brake and a steering clutch are associated to each drive sprocket in order to enable the operator to steer in the corresponding direction. In particular, if the operator desires to steer to the right along a relatively wide steering arc, he simply has to disengage the steering clutch associated with the right track. If it is instead desired to steer to the right along a relatively narrow arc, in addition to disengaging the right steering clutch the operator must also act on the brake associated to the right track. Similar operations have to be performed on the left track if it is desired to steer the vehicle to the left.
Crawler tractors are known in which steering to the right and left, as well as engaging or disengaging the main clutch, can be performed by acting on a single control lever. In particular, the operator can disengage the main clutch by pulling the control lever towards himself, engage the main clutch by moving the control lever away from himself, and steer to the right or left respectively by moving the control lever towards the right or the left.
Tractors provided with a control lever of the above-described type have the advantage of concentrating a plurality of different functions in a single lever, which enables a reduction in the number of distinct control members with which the operator has to interact. However, in order to activate the control lever the operator has to incline the upper part of his body forwards, thereby detaching his back from the seat backrest of the tractor, in particular in a case in which it is desired to engage the main clutch. These movements can cause fatigue and back-ache for the operator, especially in a case in which the operator has to stay on the tractor for a period lasting many hours consecutively, during which he frequently acts on the control lever.
Furthermore, when the operator detaches his back from the backrest in order to activate the control lever, the upper part of the operator's body does not have a fixed resting point, which can compromise the operator's safety, especially in a case in which the tractor is working on terrains with a considerable slope.
An object of the invention is to improve vehicle control devices, especially for crawler vehicles.
A further object is to provide a control device which reduces the physical fatigue and back-ache for the operator.
A further object is to provide a control device which can be activated in conditions of improved safety for the operator.
According to the invention, there is provided a control device for a crawler vehicle, comprising a control lever that is activatable by an operator about a fulcrum and has a free end, the control lever being displaceable along a longitudinal direction of the vehicle between a proximal position, closer to the operator, and a distal position, further from the operator, in order to control a main clutch of the vehicle, the device further comprising a support element suitable for being fixed to a body of the vehicle in order to support an operator's hand while said hand acts on the control lever, characterised in that the control lever has an intermediate portion interposed between the free end and the fulcrum, the intermediate portion being shaped such as partially to embrace the support element in the proximal position.
In the proximal position, the intermediate shaped portion enables the control lever to the moved closer to the support element, in comparison with a straight control lever. Therefore, for a given stroke, the distance between the control lever and the support element can also be reduced in the distal position. In this way, even in the distal position the operator can act on the control lever with the fingers of one hand, while at the same time his wrist or palm of the same hand are resting on the support element.
This enables a limiting of the operator's back movements, and reduces the frequency with which the operator is forced to detach his back from the seat's backrest. Thus physical fatigue and the risk of back-ache for the operator are consequently reduced.
Further, since the wrist or palm is kept resting on the support element even when the control lever is in the distal position, the operator finds, in the support element, a stable rest point, even where the vehicle is working on terrain exhibiting a steep slope. This increases the operator's safety.
In an embodiment, the control lever is further oscillatable in a transverse direction of the vehicle in order to steer to the right or left. An arc-shaped resting zone projects from a central region of the support element; the operator's hand can move along this resting zone when the control lever is moved in the transverse direction.
The arc-shaped resting zone enables the distance between the support element and the free end of the control lever to be maintained substantially unchanged when the control lever is moved in the transverse direction, i.e. perpendicularly to the longitudinal direction. In this way, the operator's wrist or palm can be kept resting on the arc-shaped resting zone even when his fingers move along the transverse direction in order to displace the control lever correspondingly.
Thus the safety and drive comfort of the operator can be further improved.