US 12,275,625 B2
Hydraulic system for an industrial truck
Markus Schwab, Mölln (DE); and Ulrich Knechtel, Erlenbach a. Main (DE)
Assigned to Linde Material Handling GmbH, Aschaffenburg (DE); and STILL GmbH, Hamburg (DE)
Filed by Linde Material Handling GmbH, Aschaffenburg (DE); and STILL GmbH, Hamburg (DE)
Filed on Jun. 28, 2023, as Appl. No. 18/215,220.
Claims priority of application No. 10 2022 120 009.4 (DE), filed on Aug. 9, 2022.
Prior Publication US 2024/0051806 A1, Feb. 15, 2024
Int. Cl. B66F 9/22 (2006.01); B66F 9/075 (2006.01); F15B 11/04 (2006.01)
CPC B66F 9/22 (2013.01) [B66F 9/0755 (2013.01); F15B 11/04 (2013.01); F15B 2211/40515 (2013.01); F15B 2211/4053 (2013.01); F15B 2211/40584 (2013.01)] 14 Claims
OG exemplary drawing
 
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.
 
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.