Abstract: A vehicle body frame of a bulldozer has a left side frame, a right side frame, a base plate, and a cross member. The left and right side frames each extend in the front and back direction. The base plate spans across between the left and right side frames. The cross member is positioned between a hydraulic pump and left and right hydraulic motors. The cross member protrudes upward from the base plate. The cross member spans across between the left and right side frames. The cross member has a left conduit hole and a right conduit hole which are spaced apart in a left and right direction of the bulldozer. The first and second left hydraulic fluid tubes pass through the left conduit hole. The first and second right hydraulic fluid tubes pass through the right conduit hole.

Abstract: A vehicle body frame of a bulldozer has a left side frame, a right side frame, a base plate, and a cross member. The left and right side frames each extend in the front and back direction. The base plate spans across between the left and right side frames. The cross member is positioned between a hydraulic pump and left and right hydraulic motors. The cross member protrudes upward from the base plate. The cross member spans across between the left and right side frames. The cross member has a left conduit hole and a right conduit hole which are spaced apart in a left and right direction of the bulldozer. The first and second left hydraulic fluid tubes pass through the left conduit hole. The first and second right hydraulic fluid tubes pass through the right conduit hole.

Abstract: Disclosed is a controller for construction equipment, which avoids occurrence of an engine stall even at the time of a heavy load while assuring simultaneous operation of a hydraulic actuator for a working machine and a hydraulic drive motor. The controller is provided with a torque variable control valve for controlling a pump maximum displacement so that a suction torque of a hydraulic pump becomes constant when a discharge oil pressure of the hydraulic pump exceeds a predetermined value; and a servo valve for changing the tilt angle of a cam plate of the hydraulic pump in accordance with an instruction from the torque variable control valve.

Abstract: To provide a dual tilt control system for a work vehicle, the system being capable of using a switching valve adapted to low pressure and low flow rates and left and right tilt cylinders of the same diameter and yielding large force during pitch and dual tilt operations and requiring no piston valve. A left tilt cylinder driving hydraulic circuit and a right tilt cylinder driving hydraulic circuit for respectively supplying pressure oil from a hydraulic pump to the left and right cylinders are arranged in parallel and comprise a left tilt cylinder actuation switching valve and a right tilt cylinder actuation switching valve, respectively. In a pilot pressure signal circuit for controlling the tilt cylinder actuation switching valves, a pilot switching valve for switching a blade between the pitch operation, a single tilt operation and the dual tilt operation by means of the left and right cylinders is provided.

Abstract: A steering method and steering system which enable a minimum turn radius more than the discharge capacities of a hydraulic motor and a hydraulic pump and which positively prevent the unstable traveling and turning behavior of a vehicle when the vehicle makes a pivot turn. The vehicle is provided with a pair of brakes for right and left output shafts and designed to transmit the driving force of the hydraulic motor to the output shafts through planetary gear mechanisms. During a pivot turn of the vehicle, an operation of the brake of either one of the right and left output shafts and a transmission of a driving force from the hydraulic motor to a planetary gear mechanism are simultaneously carried out for a specified period of time and thereafter, the transmission of the driving force from the hydraulic motor to the planetary gear mechanism is interrupted.

Abstract: To provide a dual tilt control system for a work vehicle, the system being capable of using a switching valve adapted to low pressure and low flow rates and left and right tilt cylinders of the same diameter and yielding large force during pitch and dual tilt operations and requiring no piston valve. A left tilt cylinder driving hydraulic circuit and a right tilt cylinder driving hydraulic circuit for respectively supplying pressure oil from a hydraulic pump to the left and right cylinders are arranged in parallel and comprise a left tilt cylinder actuation switching valve and a right tilt cylinder actuation switching valve, respectively. In a pilot pressure signal circuit for controlling the tilt cylinder actuation switching valves, a pilot switching valve for switching a blade between the pitch operation, a single tilt operation and the dual tilt operation by means of the left and right cylinders is provided.

Abstract: A controlling device for a hydraulically operated cooling fan capable of obtaining optimum cooling efficiency by continuously controlling a rotational frequency of the cooling fan according to a cooling water temperature, a hydraulic oil temperature, and an engine speed is provided.

Abstract: A steering method and steering system which enable a minimum turn radius more than the discharge capacities of a hydraulic motor and a hydraulic pump and which positively prevent the unstable traveling and turning behavior of a vehicle when the vehicle makes a pivot turn. The vehicle is provided with a pair of brakes for right and left output shafts and designed to transmit the driving force of the hydraulic motor to the output shafts through planetary gear mechanisms. During a pivot turn of the vehicle, an operation of the brake of either one of the right and left output shafts and a transmission of a driving force from the hydraulic motor to a planetary gear mechanism are simultaneously carried out for a specified period of time and thereafter, the transmission of the driving force from the hydraulic motor to the planetary gear mechanism is interrupted.