Abstract: The invention relates to a method and a device for reducing the piston speed in a piston and cylinder assembly (1), as the piston approaches the end position. The piston end position is sensed, and a signal is generated for starting the end position dampening. Dampening is effected in two steps. In the first step (14), a time delay is provided and in the next step (15), the actual braking (retardation) of the piston is effected.The invention also comprises an electronic braking device comprising a dampening activation unit (13) which is connected to transducers (6), a braking delay unit (14) connected to the unit (13) and also to the control lever (5) at issue and a reference signal source, as well as a braking unit (15) connected to the delay unit (14) and adapted, upon activation, to provide a signal (U) to a setting system (3) for controlling the supply of pressure fluid to the piston and cylinder assembly (1).

Abstract: A device for setting the speed of, in particular, an excavator engine which is to operate at a speed adapted to the type of work to be done and is automatically shifted to resting speed when no work is done. In this manner, fuel consumption and the disturbing effect of unnecessarily high noise levels are reduced. The setting device includes simple electronic control units and actuates the fuel-controlling lever of the engine fuel injection unit. A d.c. servo motor is connected to said fuel-controlling level and is supplied with a reference value signal corresponding to the desired engine speed. By manual activation of a push-button on the control lever, the device provides the possibility of manually stepping the engine working speed upwards or downwards to at least three different levels. The device also includes a resting speed unit ("idling unit") having a preset high and preset low resting speed.

Abstract: A control lever is distinctly movable in different planes for actuation of different control means. The control lever has, adjacent a control lever housing, a plate provided with a number of bevelled flat edges corresponding to the number of planes in which the control lever is movable. The plate is tiltable on its flat edges by means of movement of the lever on which is axially movable. A spring is provided between the plate and a fixed abutment on the lever for holding said lever in engagement with a seat and for urging said plate against a planar portion of the housing. When the lever is moved in a given direction, the plate is tilted or rocked about an edge against the action of the spring, with any risk of the lever moving in another undersired plane being effectively eliminated.

Abstract: To limit the power output of a hydraulic assembly consisting of plural driven hydraulic motors, hydraulic pumps driving said motors, a single pump driving motor and control means for controlling the hydraulic flow to said drive hydraulic motors, a controller is provided which is supplied with an input signal from a subtractor which in turn is supplied with signals from a reference value setting device and an actual value setting device, the actual value setting device sensing the speed of the driving motor. An output signal of the controller is applied to all of the control means and is multiplied in each control means by a signal proportional to the setting of said control means, in order to obtain the flow control signal.

Abstract: An apparatus for restricting the velocity of movement of the piston of a servo-controlled operating hydraulic unit, when the piston approaches at least its one end position in the cylinder, by means of a hydraulic sensor fixedly mounted on one of the machine parts which is shifted with respect to each other by means of the operating hydraulic unit, and is coupled by the intermediary of a non-return valve to the servo-circuit. When the piston of the operating hydraulic unit approaches its end position in the cylinder, the hydraulic sensor is actuated by the second of the above-mentioned machine parts, whereby a pressure is established in the cylinder of the hydraulic sensor which exceeds the servo-pressure. A valve senses the pressure difference between the servo-pressure and the pressure established by means of the hydraulic sensor and throttles the servo-flow to the main valve of the operating hydraulic unit the main valve thereby throttling the pressure medium supply to the operating hydraulic unit.

Abstract: A valve block for hydraulic excavators having at least two sets of valves which are each coupled to their pump. The valves are of the type which, in the unactuated state, allows the passage of pressure medium. The hydraulic devices for executing working movements of the excavator are each coupled to their valve in each set. The valves in the one set are coupled in series, counted from the pump in the sequence the valve which is coupled to the hydraulic device for the first working movement of the excavator, the valve which is coupled to the hydraulic device for the second working movement of the excavator, and the valve which is coupled to the hydraulic device for the third working movement of the excavator.

Abstract: Measurement devices are provided on the boom and stick of an excavator and are diposed to measure, by means of the gravitational force, the angle of the boom and the stick, respectively, relative to the horizontal plane. These measurement values are applied to an evaluation instrument which indicates the excavation depth on the basis of the length of the boom and the stick and with the help of the received values. Furthermore, means may be provided to measure the lifting force exercised by the boom ram, this measurement being also applied to the evaluation instrument whereby it can, by means of the first-mentioned measurement values, also indicate the turning moment exercised on the boom and the stick.

Abstract: A speed regulator for an engine of an earth mover and worker, particularly a diesel engine of an excavator, said speed regulator including an operating member which comprises a piston and cylinder unit and is connected into the linkage between the fuel supply regulating means of the engine and a manually operable lever, the feed and outlet lines of the piston cylinder unit being coupled to a control circuit which is connected to the operating system for the implements of the earth mover and worker.