ACTUATOR FOR AIDING HITCHING OF AN IMPLEMENT TO A TRACTOR

Abstract: The present invention relates to an actuator device for aiding the hitching of an implement (1) to the three-point linkage of a tractor (2) or similar pulling vehicle. According to the invention, the actuator device comprises a double-acting hydraulic cylinder (5), which is mountable between two pulling links (3) of the tractor's three-point linkage for controlled adjustment of the mutual distance between the pulling links (3), and said hydraulic cylinder (5) is connectable to a two-way directional control valve bank (4) of the hydraulic system of the tractor. To avoid mechanical overload of the pulling links (3), the cylinder (5) is manufactured with a piston clearance providing an internal bypass flow path.

Description: ACTUATOR FOR AIDING HITCHING OF AN IMPLEMENT TO A TRACTOR The present invention relates to an actuator intended to aid hitching of an implement to a three-point linkage of a tractor or similar pulling vehicle. With the greater size and weight of modern equipment, the moving of tractors as well as implements has become exces¬ sively complicated. Consequently, proper location of the tractor and the manual hitching of the implement pulling linkage can be an extremely difficult and even potentially dangerous operation, which moreover is time-consuming. It is an object of the present invention to overcome such problems by virtue of an actuator device being characte¬ rized by a double-acting hydraulic cylinder being mountable between two pulling links of the tractor's three-point linkage for controlled adjustment of the mutual distance between the pulling links, said hydraulic cylinder being connectable to a two-way directional control valve bank of the hydraulic system of the tractor. With the help of the actuator device according to the invention, hitching of the implement can be carried out without the need for the driver to leave the cabin for hitching, since the function of the hydraulic cylinder can be controlled by the control levers of the tractor's hydraulic systems which are located in the tractor cabin. Further characteristics of the present invention will appear from the enclosed claims. Owing to the simple construction of the actuator device according to the invention, the device is extremely durable and reliable in use. The invention will now be described in greater detail with reference to the appended drawings, in which: Figure 1 is a perspective view of an actuator device according to the invention mounted to a tractor; and Figure 2 is a top view of the actuator device illustrated in Fig. 1 with an implement hitched to the pulling links. With reference to Fig. 1, the actuator device according to the invention for aiding the hitching of an implement 1 to the three-point linkage of a tractor 2 or similar pulling vehicle comprises a double-acting hydraulic cylinder 5, which is mountable between two pulling links 3 of the three-point linkage of the tractor 2 for controlled adjustment of the mutual distance between the pulling links, which hydraulic cylinder is connectable to a two-way directional control valve bank 4 of the tractor's hydraulic system. To perform its function, the hydraulic cylinder 5 is mounted between the two parallel pulling links 3 of the tractor 2 so that its cylinder portion 5a is connected to one pulling link 3, while its piston rod 5b is connected to the opposite pulling link 3. The hydraulic cylinder 5 is adapted to be powered by the conventional hydraulic system of the tractor via two hydraulic oil hoses 6 connected to a two-way directional control valve bank 4 of said hydraulic system, said hoses 6 advantageously being attached to said control valve bank 4 by means of quick-release connectors 6a. By virtue of this arrangement, the operation of the hydraulic cylinder 5 can then be controlled by control levers located in the tractor cabin 7 of the tractor as a standard accessory of the tractor. To achieve a construction which is maximally simple and safe in use, the hydraulic cylinder 5 is advantageously manufactured with an approx. 0.10 - 0.20 mm clearance between the cylinder inner wall and the piston without using any seal to bridge the clearance. Then, the piston can be advantageously manufactured from a bearing alloy. This arrangement ensures that the piston inherently provides a bypass channel for a certain amount of hydraulic oil thus preventing excessive load on the pulling links 3 notwithstanding the direct connection of the hydraulic cylinder to the tractor's hydraulic system without using any pressure reducing means. Such an arrangement also permits floating movement of the pulling links 3 during the time the hydraulic cylinder 5 is not powered. The mounting of the hydraulic cylinder can be modified so as to cause minimal disturbance to the use of the power take-off shaft of the tractor. By providing the pulling links 3 of the tractor 2 with quick-release joints, the hydraulic cylinder 5 can be made easily detachable and transferrable to another tractor 2 having compatible cylinder end joints. With reference to Fig. 2, the function of the actuator device according to the invention is as follows. To hitch an implement 1 to the three-point linkage of a tractor 2, the tractor 2 is initially reversed in front of the implement 1 and the pulling hole 8 of one pulling link 3 of the tractor linkage is aligned with the compatible pulling pin 9 of the implement. Next, the hydraulic cylinder 5 is activated by operating the control lever of the control valve bank 4 so that the hydraulic cylinder 5 is powered to actuate the pulling links 3 with a pulling force. Then, the pulling link 3 is moved toward the pulling pin 9 of the implement 1 so as to locate the pin through the pulling hole 8 of the pulling link 3. With the pulling pin 9 now engaged in the pulling hole 8, the pulling links 3 of the tractor are lifted at a moderate force by operating another control lever of the tractor hydraulic system until the friction of the pin in the hole is sufficient to keep the pulling pin 9 of the implement in place in the pulling hole 8 during the subsequent hitching step of the implement. In this step, the hydraulic cylinder 5 is controlled to actuate in the opposite direction so that the pulling links 3 are forced to away from each other. Next, the pulling hole 8 of the opposite side pulling link 3 is aligned in front of the mating pulling pin 9 of the implement, after which the hydraulic cylinder 5 is powered to actuate a pulling force between the links. Then, the opposite side link 3 is moved toward the pulling pin 9 of the implement so as to locate the pin through the pulling hole 8 of the pulling link 3. After the hitching of the implement is safely and easily accomplished in the above-described manner, the driver can leave the cabin 7 and secure the implement by inserting securing pins into holes drilled to the ends of the pulling pins 9 of the implement. To prevent undesirable lateral swing of the pulling links 3, both sides of the tractor 2 can be provided with conventional lateral movement limiters 10 adapted between the tractor chassis and said pulling link 3. By virtue of the invention, the unhitching of the implement 1 from the pulling links 3 of the tractor is made extremely simple. After the securing pins are removed from the ends of the pulling pins 9, the pulling pins 9 can be released from the pulling links 3 by controlling the hydraulic cylinder 5 to push the pulling links apart from each other.

Claims: Claims : 1. An actuator device for aiding hitching of an implement (1) to a three-point linkage of a tractor (2) or similar pulling vehicle, characterized by a double-acting hydraulic cylinder (5) being mountable between two pulling links (3) of the tractor's three-point linkage for controlled adjustment of the mutual distance between the pulling links (3), said hydraulic cylinder (5) being connectable to a two-way direction al control valve bank (4) of the hydraulic system of the tractor. 2. An actuator device as defined in claim 1, charac¬ terized in that the hydraulic cylinder (5) is provided with a clearance of approx. 0.1 — 0.2 mm between the cylinder inner wall and the piston. 3. An actuator device as defined in claim 1 or 2, charac¬ terized in that the hydraulic cylinder (5) is adapted to be detachably connectable to the pulling links (3) of the tractor (2) with the help of quick-release joints mounted to the ends of said pulling links (3) .

Inventors: PELTOLA TUOMO, PELTOLA, TUOMO
Applicants: PELTOLA TUOMO, PELTOLA, TUOMO
Application year: 1995
Main classification: A01B59
IPC codes: A01B59