Samsung Heavy Industries Co., Ltd.

Dae S Chung

A straight travelling apparatus for heavy construction equipment, equipped with a travel supplement circuit, including a variable orifice disposed in a fluid line connected to the supply-side of the control valve of a bucket and controlled to vary an opening degree thereof by a predetermined pilot signal that is applied to the variable orifice in response to an operation of at least one of right and left travel motors in order to keep the variable orifice at a relatively closed state while being released in response to the travel motors not operating in order to keep the variable orifice in a relatively opened state, thereby capable of supplementing a sufficient amount of fluid to a travelling system when the bucket is operated during, thereby preventing an abrupt reduction in travelling speed caused by operatings the straight travelling apparatus.

Straight travelling apparatus for heavy construction equipment

A motor cavitation prevention device for hydraulic systems is disclosed. The device exerts no influence upon return fluid of any actuators other than the hydraulic motor thereby preventing undesired pressure loss of the return line. The device has valve means installed in a given position of the return line such that the return fluid of the motor necessarily passes the check valve prior to returning to a return tank but the return fluid of the other actuators does not pass the check valve, and a feedback line for feeding the return fluid of the motor back to the motor in the ease of generation of the pressure above tank in the return line, one end of which feedback line is connected to the return line at the front of the check valve but the other end of which feedback line is connected to the motor.

Motor cavitation prevention device for hydraulic systems

A delivery control device for hydraulic pumps suitable for controlling the pump delivery such that the pump's delivery characteristics are not influenced by load acting on actuators is disclosed. The device also reduces the pump delivery in cases where no actuator is being operated but instantly increases the pump delivery in the event either actuator is operated. The device has a branch line branched from a pilot line and adapted for draining the swash plate's regulating pilot oil from the pilot line to a return tank, and a relief valve provided in the branch line, selectively opened in response to a preset pressure applied thereto. The preset pressure for opening the relief valve is the delivery pressure of the hydraulic pump.

Delivery control device for hydraulic pumps and hydraulic systems with

A variable priority device for heavy construction equipment for establishing a priority of the boom over the bucket by limiting an amount of fluid passing through a bucket-side parallel fluid line when the boom operates alone and thereby decreasing the amount of fluid supplied to the bucket actuator. The device is installed in the bucket-side parallel fluid line and adapted to be switched between an orifice state and an orifice release state, the priority control valve being initially maintained at the orifice release state by a resilience device while being switched from the orifice release state to the orifice state against a resilience of the resilience device in response to a pilot pressure for moving the spool of a boom-side switching valve communicating with the boom actuator.

Variable priority device for heavy construction equipment

A priority control valve used in a hydraulic apparatus for supplying fluid delivered from a single pump to at least two actuators respectively via parallel fluid lines, the actuators operating independently or in combination with each other. The variable priority device includes a priority control valve installed in the parallel fluid line associated with one of the actuators and adapted to be switched between an orifice state and an orifice release state, the priority control valve being initially maintained at the orifice release state by resilience means while being switched from the orifice release state to the orifice state against a resilience of the resilience means in response to a pilot pressure for moving the spool of a control valve for the other actuator. A feedback fluid line is connected between the parallel fluid line associated with the one actuator and the priority control valve to apply a fluid pressure exerted therein to the priority control valve against the pilot pressure so that the priority control valve can be switched from the orifice state to the orifice release state in response to an increase in fluid pressure in the associated parallel fluid line.

Variable priority device

A device for sensing actuator operating signal in a hydraulic system is disclosed. The device has auxiliary valves directly coupled to the directional control valves respectively, the internal lines of which auxiliary valves are opened or become orifices in accordance with positions of spools of their associated directional control valves. A fluid line extends from a hydraulic pump to a return tank after passing the auxiliary valves in a series. The device also has two elements for detecting fluid pressure at two given points along the fluid line. An additional orifice is formed in the hydraulic line between the auxiliary valves and the pressure detecting elements is provided in the hydraulic line before and after the additional orifice.

Actuator operating signal sensor

A straight travelling apparatus for heavy construction equipment such as excavator or crane, including a straight travel valve disposed in both lines respectively branching from first and second hydraulic pumps and switched between a first state at which a fluid delivered from the first hydraulic pump is supplied to a right travel motor and a part of the actuators of a working system while a fluid delivered from second hydraulic pump is supplied to a left travel motor and the remaining part of the actuators of the working system and a second state at which the fluid delivered from the first hydraulic pump is supplied to both the right and left travel motors while the fluid delivered from the second hydraulic pump is supplied to all actuators of the working system, first and second pilot fluid lines both branching from the pilot pump, a connecting fluid line adapted to communicate the first and second pilot fluid lines with each other, a fluid line branching from the connecting fluid line, and a relief check valve disposed at a predetermined position between a branching point where the fluid line branches from the connecting fluid line and a connecting point where the connecting fluid line is connected to the second pilot fluid line.

Growing community of inventors

Pusan, South Korea

Dae S Chung