Granted Patent B2

US 12,275,625 · App. 18/215,220 · Granted Apr 15, 2025

Inventors: Markus Schwab (Mölln, DE); Ulrich Knechtel (Erlenbach a. Main, DE)

Assignees: Linde Material Handling GmbH; STILL GmbH

B66F9/22B66F9/0755F15B11/04F15B2211/40515F15B2211/4053F15B2211/40584

Abstract

Claims (28)

1. A hydraulic system for an industrial truck with a lifting frame, at least one telescoping mast that can be raised and lowered in a stationary mast, and a load handling device that can be raised and lowered in the telescoping mast, wherein the hydraulic system comprises:

a free lift cylinder for raising and lowering the load handling device; and

at least one mast lift cylinder for raising and lowering the telescoping mast,

wherein a control valve device is provided for the control of the lifting operation and the lowering operation of the free lift cylinder and of the mast lift cylinders,

wherein a mast transition damping device is provided that comprises at least one electrically actuated proportional valve,

wherein the proportional valve of the mast transition damping device, in an unactuated state, has a throttling connection that effects a throttled volume flow, and in the event of an electrical control action, can be actuated toward an open position, and

wherein the proportional valve is located in a housing, wherein the proportional valve in the unactuated state is actuated into a normal position which is in the form of a closed position, and the throttling connection is formed by a bypass line in the housing of the proportional valve in which a throttling device is located.

2. The hydraulic system according to claim 1 , wherein the proportional valve in the unactuated state is actuated into a normal position which is provided with the throttling connection.

3. The hydraulic system according to claim 1 , wherein the free lift cylinder is connected by a first branch line with the control valve device, and the at least one mast lift cylinder is connected by a second branch line with the control valve device, wherein there is a first proportional valve of the mast transition damping device in the first branch line and a second proportional valve of the mast transition damping device in the second branch line.

4. The hydraulic system according to claim 3 , wherein the first proportional valve is attached to the free lift cylinder and has the function of an electrical line break safety device.

5. The hydraulic system according to claim 1 , wherein a mechanical line break safety device is attached to each mast lift cylinder.

6. The hydraulic system according to claim 1 , wherein a mechanical line break safety device is attached to the free lift cylinder.

7. The hydraulic system according to claim 1 , wherein the free lift cylinder is connected by a first branch line with the control valve device, and each mast lift cylinder is in communication by a connecting line with the control valve device, wherein a proportional valve of the mast transition damping device is located in each of the first branch line and the connecting line.

8. The hydraulic system according to claim 7 , wherein attached to the free lift cylinder is a first proportional valve and/or attached to each mast lift cylinder is a second proportional valve, wherein the first and second proportional valves each have the function of an electrical line break safety device.

9. A hydraulic system for an industrial truck with a lifting frame, at least one telescoping mast that can be raised and lowered in a stationary mast, and a load handling device that can be raised and lowered in the telescoping mast, wherein the hydraulic system comprises:

a free lift cylinder for raising and lowering the load handling device; and

at least one mast lift cylinder for raising and lowering the telescoping mast,

wherein a control valve device is provided for the control of the lifting operation and the lowering operation of the free lift cylinder and of the mast lift cylinders,

wherein a mast transition damping device is provided that comprises at least one electrically actuated proportional valve,

wherein the proportional valve of the mast transition damping device, in an unactuated state, has a throttling connection that effects a throttled volume flow, and in the event of an electrical control action, can be actuated toward an open position,

wherein the free lift cylinder is connected by a first branch line with the control valve device, and the at least one mast lift cylinder is connected by a second branch line with the control valve device,

wherein there is a first proportional valve of the mast transition damping device in the first branch line and a second proportional valve of the mast transition damping device in the second branch line, and

wherein located on the first proportional valve is a bypass line in which there is a stop valve that opens toward the control valve device.

10. The hydraulic system of claim 9 , wherein the proportional valve in the unactuated state is actuated into a normal position which is provided with the throttling connection.

11. The hydraulic system of claim 9 , wherein the proportional valve in the normal position is provided with a throttling opening.

12. The hydraulic system of claim 9 , wherein located on the second proportional valve is a bypass line in which there is a stop valve that opens toward the at least one mast lift cylinder.

13. The hydraulic system of claim 9 , wherein a mechanical line break safety device is attached to each mast lift cylinder.

14. The hydraulic system of claim 9 , wherein a mechanical line break safety device is attached to the free lift cylinder.

Assignments (1)

Priority Claims (1)

Continuity (1)

References Cited (9)