Abstract: An automatic control method for a taphole opener for opening a taphole by giving impact and rotation to a drill unit holding a drilling rod and driving the drill unit forward and backward by a hydraulically driven feed motor, which method comprises the steps of; detecting the driving load in the form of detected hydraulic pressure, stopping the driving but maintaining the rotation when said detected pressure reaches an upper limit set value beyond which buckling may occur, and resuming the driving when said detected pressure falls to a lower limit set value or below. The drilling rod of the drills unit is prevented from buckling and idle hitting and a quicker taphole opening operation and enhanced accuracy of taphole depth can be obtained. Thus remote operation is made possible through the automation of the taphole opening work.

Abstract: An engine brake system comprising, in combination, a power absorbing oil pump driven in operative linkage with the crank shaft of the engine and a mechanism for controlling discharge pressure of said oil pump is disclosed. The pressure control mechanism comprises a main valve designed to be opened with a lift inversely proportional to the braking torque of the engine, a mechanism for adjusting the pressure on the back side of the main valve and a valve for switching the pressure on the back side of the main valve, all of which are provided in a valve box having an oil hole communicated with the discharge port of the oil pump. According to this system, in accordance as the engine speed increases, the lift of the main valve is reduced to elevate the power absorbed by the oil pump. Thus, this system is particularly useful for engine brake for vehicles.