Abstract: A hydraulic actuator for a hydraulic servomotor (4) is disclosed. The hydraulic servomotor (4) is of a kind having at least one defined end position, and has a first chamber (5) and a second chamber (6) associated therewith. The actuator is connected to a fluid source (2) and a fluid drain (3). The actuator comprises a first valve (7) fluidly connected between the fluid source (2) and the first chamber (5), a second valve (8) fluidly connected between the first chamber (5) and the fluid drain (3), and a third valve (9) fluidly connected between the fluid source (2) and the second chamber (6). The actuator further comprises a flow channel (10, 17), preferably comprising a flow restrictor (12, 18), in fluid communication with the second chamber (6). The valves (7, 8, 9) are such that, in the case of a power cut off, they will prevent a fluid flow out of the first chamber (5), and a fluid flow out of the second chamber (6) takes place via the flow channel (10, 17).

Abstract: A hydraulic actuator for a hydraulic servomotor 4 is disclosed. The hydraulic servomotor 4 has a first chamber 5 and a second chamber 6 associated therewith. The hydraulic actuator is connected to a fluid source 2 and a fluid drain 3, and it comprises a valve assembly arranged between the fluid source 2 and the fluid drain 3 to control fluid pressures in the chambers 5, 6. At least one auxiliary valve 11 is fluidly connected between the valve assembly and the fluid drain 3, said auxiliary valve(s) 11 being of a kind which is normally closed in a de-energized state. In the case of a power cut off the auxiliary valve(s) 11 will close, thereby preventing fluid flow from the valve assembly towards the fluid drain 3. This causes a servomotor piston member 12 to be hydraulically locked in its instantaneous position, thereby locking the hydraulic servomotor 4. The valve assembly may be designed without taking the locking function into consideration.

Abstract: A control system for a hydraulic servomotor (13) is disclosed. The control system comprises an electro hydraulic actuator (2) comprising a number of valves (9, 10, 11, 12, 18) for controlling fluid flows, a main control module (1), and one or more connectors. The control system further comprises at least one extension control module (3) comprising one or more connectors. Finally, the control system comprises means (6) for communicating signals between the main control module (1) and each of the extension control module(s) (3). Since the main control module (1) and the extension control module(s) (3) are able to communicate signals, it is possible to provide signals to/from the main control module (1) via an extension module (3), thereby in effect providing additional connectors to the main control module (1). Thereby the main control module (1) may be able to perform additional functions as compared to similar prior art control modules.

Abstract: The invention concerns a hydraulic machine with a toothed set comprising a toothed ring with an inner toothing, whose circumferential surface extends in parallel with its axis, and a gear wheel (3) with an outer toothing, whose circumferential surface (24) extends in parallel with its axis, at least one tooth flank having an edge as an axial end of a section, which is located between the circumferential surface and a surface directed radially inwards. It is endeavored to reduce the wear. For this purpose it is ensured that in the radial direction an edge (22, 23) ends so as to be offset inwards in relation to the circumferential surface (24).

Abstract: The invention concerns a valve arrangement (1) with a high-pressure connection (P), a low-pressure connection (T), at least one control valve (2 to 5), which is accommodated in a control valve module and has at least one working connection (A, B) for a hydraulic consumer (7 to 10), and a safety valve (6), which is accommodated in a safety valve module, and which releases or blocks a passage between the high-pressure connection (P) and the control valves (2 to 5), the control valve module (2 to 5) and the safety valve module (6) being connected to one component group. It is endeavoured to provide a valve arrangement with a high safety level. For this purpose, it is ensured that each control valve (2 to 5, 2? to 5?) has an error detection device (19), that the safety valve module (6) has a safety switch device (21) and that the component group has a connection (20) between the safety switch device (21) and the error detection device (19).

Abstract: The invention concerns a hydraulic steering arrangement (1) with a supply connection arrangement (P, T), a working connection arrangement (A, B) connectable to a steering motor (5), a steering unit (6) located between the supply connection arrangement (P, T) and the working connection arrangement (A, B), and a steering valve (14) whose outlet is connected to the working connection arrangement (A, B). It is endeavoured to keep the load of such a steering arrangement small. For this purpose, the steering unit (6) is made as an open-center steering unit, an inlet (20) of the steering valve (14) being connected to a pressure supply arrangement (22) that can be activated by an activation of the steering valve (14).

Abstract: The invention concerns a hydraulic control (1) with a supply connection arrangement (7) having a high-pressure connection (P) and a low-pressure connection (T), a working connection arrangement having two working connections (A, B) connectable with a consumer, a control valve (8) with a valve element (9) between the supply connection arrangement and the working connection arrangement and a compensation valve (11), which is located between the high-pressure connection (P) and the control valve (8) and is acted upon in the closing direction by a pressure between the compensation valve (11) and the control valve (8). It is endeavoured to ensure the most favourable energy consumption possible. For this purpose, in the opening direction the compensation valve (11) is acted upon by a pressure of a selection device (29, 30, 30?, 38), which optionally supplies the compensation valve (11) with a pressure control pressure or a flow control pressure.

Abstract: The invention concerns a hydraulic valve arrangement (1) with a control valve module (2) comprising a supply connection arrangement with a high-pressure connection (P) and a low-pressure connection (T) and a working connection arrangement with two working connections (A, B) as well as a control valve (3) between the supply connection arrangement and the working connection arrangement. It is endeavored to improve the control behavior of the valve arrangement. For this purpose. it is ensured that the control valve module (2) has a return compensation valve (15, 16) between the control valve (3) and at least one working connection (A, B).

Abstract: The invention provides a fluid controller for controlling a machine, e.g. for steering a vehicle. The controller comprises a housing defining an inlet port connected to the source and an outlet port connected to the pressure operated device. The flow rate is controlled by movement of a valve member within the housing, and a processor provides a reference which is indicative of a desired position of the valve member relative to the housing. The fluid controller comprises a fault detection system based on an observer. The observer calculates a theoretically correct position of the valve member relative to the housing for a given reference, and compares this position to an obtained position of the valve member relative to the housing. The difference between the positions is compared with a threshold value. In order to dynamically change the sensitivity of the system, the threshold value is scaled based on a gradient of the reference.

Abstract: The invention concerns a hydraulic steering with a steering motor arrangement, a steering valve arrangement and a pressure supply comprising a first pump and a second pump. It is endeavoured to perform a change between the supplies by the pumps as unperceived as possible. For this purpose, the steering valve arrangement (4) is connected to the first pump (6) through a valve (8) with pressure compensation function and to the second pump (19) through a compensation valve (26).

Abstract: The invention concerns a hydraulic steering with a steering motor arrangement having at least one steering motor, and with at least two steering circuits, each having a steering valve that interrupts a path from a pressure supply to the steering motor arrangement in the neutral position and releases a path from the pressure supply to the steering motor arrangement on a movement out of the neutral position. It is endeavoured to simplify the embodiment of such a steering. For this purpose, the steering valve (5a, 5b) has two end positions, one on each side of the neutral position, in which positions a path from the pressure supply (15, 21) to the steering motor arrangement (2) is interrupted.

Abstract: An object comprising a body part having an electrically insulating outer surface part, and a first layer arranged on the outer surface part. The first layer is formed by one or more electrically conducting materials and defines one or more conducting paths between a first area of the outer surface part and a second area of the outer surface part. Thereby electrical signals may be transferred between the first and second area parts. The layer further defines a sensing device, which is thereby embedded into the object. The object is provided with a threaded portion defining an outer thread. Thereby the object may easily be fitted into an opening having a mating inner thread. The object may be in the form of an ordinary bolt with a sensing device embedded in a surface part thereof.

Abstract: The invention concerns a hydraulic steering (1) with a steering unit (2) with feedback behaviour, a steering motor (8) connected to the steering unit (2) via working pipes (L, R), a steering member (6) and a feedback suppression device (9), which is located in at least one working pipe (L, R). It is endeavoured to change the feedback behaviour of such a steering in a simple manner. For this purpose, the feedback suppression device (9) has a valve arrangement (10) with hydraulic control inlet (C).

Abstract: The invention concerns a hydraulic steering (1) with a steering motor (8), a steering unit (2) with feedback behaviour, a steering member activating the steering unit (2) and a shock valve arrangement (50) between the steering motor (8) and the steering unit (2). It is endeavoured to enable changes of the feedback behaviour in a simple manner. For this purpose it is ensured that a switchable feedback suppression device (9) is located at the side of the shock valve arrangement (50) facing away from the steering motor (8).

Abstract: The invention concerns a hydraulic steering (1) with a steering valve (7) located between a supply connection arrangement (P, T) and a steering motor (2). It is endeavoured to improve the safety of such a steering. For this purpose, the steering valve (7) has a hydraulic drive (9, 10) with a pilot valve arrangement (11) supplied by a pressure control valve (5), a stop valve (16) being located between the pressure control valve (5) and the pilot valve arrangement (11).

Abstract: The invention concerns a hydraulic valve arrangement (1) with a working connection arrangement having a first working connection (A) and a second working connection (B), both working connections (A, B) being connectable with a hydraulic consumer (2), a supply connection arrangement having a pressure connection (P) and a tank connection (T), a first valve arrangement with a first valve (12), closing the pressure connection (P) or connecting it in a controlled manner with the first working connection (A) or the second working connection (B), a second valve arrangement with a second valve (16), closing the tank connection (T) or connecting it in a controlled manner with the first working connection (A) or the second working connection (B), and a control arrangement controlling the first valve arrangement and the second valve arrangement. In such a valve arrangement, it is endeavoured to achieve improved operation behaviour.

Abstract: A hydraulic machine has a gear wheel (2) with outwardly extending teeth and a gear ring (4) with inwardly extending teeth formed by rollers each of which is supported in a pocket (8) in the gear ring, and pressurized spaces are formed between the gear wheel and the inwardly extending teeth. To keep the wear of the machine small each pocket (8) has at least two different radii (R1, R2, Rn) whereby a radius (R2, Rn) at a smaller displacement from the edge (12) of the pocket is larger than a radius (R1) at a larger displacement from the same edge (12) of the pocket (8).

Abstract: The invention provides a fluid controller, e.g. for a hydrostatic power steering. The controller comprises a cylindrical valve member cooperating with a housing to define at least one fluid path from a pressure source to a steering cylinder. The valve member is rotatable in the housing and comprises a sleeve and a spool, wherein the spool is rotatable within the sleeve. The fluid flow is metered by a flow meter, and the valve member comprises a plurality of meter ports communicating the fluid between the valve member and the flow meter. To obtain less friction between the sleeve and the housing and between the sleeve and the spool, the meter ports are grouped in two groups in which groups the ports are in mutually fluid communication.

Abstract: The invention concerns a valve arrangement for controlling a hydraulic drive, the supply to and the outflow from the hydraulic drive being separately controllable. It is endeavoured to realise separate controls of the speed and the hydraulic pressure of the hydraulic drive. For this purpose, a pump pipe is connected with a first control valve, the first control valve is connected through a pipe with a first working connection and a second working connection of the hydraulic drive, and the first working connection is connected with a second control valve and the second working connection is connected with a third control valve, the second control valve and the third control valve opening into a tank (T).

Abstract: The invention concerns a valve arrangement (1) with at least two valve modules (2, 4, 5), each having a valve element, whose position can be changed by means of an actuator (13, 13a, 13b), and to which a position sensor (19, 19a, 19b) is allocated, a line arrangement (24) being connected with the valve modules (2, 4, 5), through which control signals can be transmitted to the valve modules (2, 4, 5). It is endeavoured to increase the safety of such valve modules. For this purpose, at each valve module (2 to 5) the actuator (13) is provided with a control device (22, 22a, 22b), which is connected with the position sensor (19, 19a, 19b) and evaluates control signals for the valve module (2 to 5) concerned, that at least the control device (22b) of a first valve module (5) additionally evaluates the control signals for another, second valve module (4), and that this control device (22b) receives signals from the position sensor (19a) of the second valve module (4).