Adjustable fork for heavy loads

An adjustable fork, comprising:

• a main frame (2);
• a first and a second prong (5, 6), associated with the main frame (2);
• a first slider (3) and a second slider (4), associated with the main frame (2);
• the first slider (3) is slidable along an adjustment direction (X) away from and towards the second slider (4) for a predetermined adjustment stroke of the first slider (3);
• the second slider (4) is slidable along the adjustment direction (X) away from and towards the first slider (3) for a predetermined adjustment stroke of the second slider (4);
• the first prong (5) is associated with the first slider (3) and is slidable, relative to the first slider (3), along the adjustment direction (X) for a predetermined adjustment stroke of the first prong (5);
• the second prong (6) is associated with the second slider (4) and is slidable, relative to the second slider (4), along the adjustment direction (X) for a predetermined adjustment stroke of the second prong (6);
• a first actuator (30), connected to the first slider (3) and designed for determining the adjustment stroke of the first slider (3);
• a second actuator (40), connected to the second slider (4) and designed for determining the adjustment stroke of the second slider (4);
• wherein the first prong (5) is slidable on the first slider (3) such that the first prong (5) is slidable in front of the first actuator (30);
• wherein the second prong (6) is slidable on the second slider (4) such that the second prong (6) is slidable in front of the second actuator (40).

An adjustable fork, comprising:

• a main frame (2);
• a first and a second prong (5, 6), associated with the main frame (2);
• a first slider (3) and a second slider (4), associated with the main frame (2);
• the first slider (3) is slidable along an adjustment direction (X) away from and towards the second slider (4) for a predetermined adjustment stroke of the first slider (3);
• the second slider (4) is slidable along the adjustment direction (X) away from and towards the first slider (3) for a predetermined adjustment stroke of the second slider (4);
• the first prong (5) is associated with the first slider (3) and is slidable, relative to the first slider (3), along the adjustment direction (X) for a predetermined adjustment stroke of the first prong (5);
• the second prong (6) is associated with the second slider (4) and is slidable, relative to the second slider (4), along the adjustment direction (X) for a predetermined adjustment stroke of the second prong (6);
• an actuator unit (30, 40, 50, 60), designed for determining said adjustment strokes of the first slider, the second slider, the first prong and the second prong;
• a control system, connected to the actuator unit (30, 40, 50, 60) and configured for activating the actuator unit in response to at least one widening command and to a narrowing command;
• wherein in a presence of an active widening command, the control system determines a moving of the prongs (5, 6) away from each other up to a maximum distance position, followed by a moving away from each other of the sliders (3, 4);
• wherein in a presence of an active narrowing command, the control system determines a moving of the prongs (5, 6) towards each other up to a minimum distance position, followed by a moving towards each other of the sliders (3, 4);
• a first actuator (30), connected to the first slider (3) and designed for determining the adjustment stroke of the first slider (3);
• a second actuator (40), connected to the second slider (4) and designed for determining the adjustment stroke of the second slider (4);
• a third actuator (50), connected to the first prong (5) and designed for determining the adjustment stroke of the first prong (5);
• a fourth actuator (60), connected to the second prong (6) and designed for determining the adjustment stroke of the second prong (6);
• wherein the control system is connected to said actuators (30, 40, 50, 60) and is configured for activating each actuator in response to said widening and narrowing commands;
• wherein said actuators (30, 40, 50, 60) are hydraulic actuators, and wherein the control system comprises a hydraulic circuit;
• wherein said actuators (30, 40, 50, 60) each comprise a first chamber (C1) and a second chamber (C2), separated from each other by a piston (P), and wherein the control system comprises:
• a first supply line (7), which connects the first chamber (C1) of the third and fourth actuators (50, 60) with a first coupling opening (V1);
• a second supply line (8), which connects the second chamber (C2) of the third and fourth actuators (50, 60) with a second coupling opening (V2);
• a third supply line (9), which connects the first chamber (C1) of the first and second actuators (30, 40) with said first coupling opening (V1);
• a fourth supply line (10), which connects the first chamber (C1) of the first and second actuators (30, 40) with said second coupling opening (V2);
• a first distributor (D1), connected to the first and second coupling openings (V1, V2), which may adopt a first position, in which the first distributor connects the first coupling opening (V1) with a source of pressurised fluid and the second coupling opening (V2) with a discharge, a second position, in which the first distributor connects the first coupling opening (V1) with said discharge and the second coupling opening (V2) with said source of pressurised fluid, and a central position, in which neither of the two coupling openings is connected to the source of pressurised fluid;
• sequence means which, with the first distributor (D1) in the first position, are designed to direct the pressurised fluid to the first supply line (7) until reaching a predetermined pressure and, subsequently, to direct the pressurised fluid to the third supply line (9);
• with the first distributor (D1) at the second position, the sequence means are set up to direct the pressurised fluid to the second supply line (8) until reaching a predetermined pressure and, subsequently, to direct the pressurised fluid to the fourth supply line (10).