The master cylinder is linked to the accelerator pedal. The press^jre generated in it actuates the control cylinder on the lower structure to accelerate the engine when the crane is operated.
The control cylinder, actuated by the pressure from the master cylinder, accelerates the engine during crane operation.
When push rod recedes, the oil in the actuator cylinder is pushed back by the actuator return spring and spring (7-9) If push rod recedes quickly and piston (7-1) moves faster than the speed of returning oil, the pressure in the master cylinder tends to become negative. If this occurs, valve cup is unseated, allowing oil to flow from chamber В into the master cylinder. As pistonmoves toward the stroke end, stopper (6) pushes valve rod (7-5) to open valve cup (7-6) thereby allowing excess oil in the cylinder to return to chamber В via the passage in valve rod (7-5) . Check valve serves to leave a 0.2 — 0.5kg/cm residual pressure in the actuator cylinder and piping, even when piston (7-1) is fully returned. This pressure allows the cylinder cup to remain in contact with the cylinder wall, to prevent leakage; the pressure also protects the system from air entry through connections.
Metal parts Wash in trichloroethylene, and dry by blowing compressed air on them. In the weight table below, the weights of major components are given in terms of weight codes A through T by crane spec. Nos. When dismounting and remounting these components, find their approximate weight given in the table under the applicable Spec. No. and select proper slinging tools on the basis of the given weight.
The moment detector is incorporated in the elevating cylinder piston rod, and converts, by means of strain gauges, the total moment created by the hoisted load and the boom self-weight into an electric signal that is transmitted to the moment limiter main body.
Moment limiter main body
The moment limiter main body makes the calculation of the moment being generated on the crane, using the signals from the moment detector, boom length detector and boom angle detector.
The calculation result is compared with the rated moment and, when it reaches 90% and 100% of the rating, the moment limiter sends an alarm and auto, stop signals, respectively, to prevent the crane from being over-loaded.
Solenoid valve 2.
If the AML gets out of order on when the actual moment reaches 100% of the rating or the hook block is overhoisted, an electric signal (auto, stop) is send from the moment limiter main body to this valve. When the solenoid valve is of a normally energized type, it is then de energized. When it is of a normally de-energized type, it is then energized .
Irrespective of the type of solenoid valve, this valve serves to lead the vent circuits for the relief valves incorporated in the manual control valve to the tank. The pressurized oil from the pump is then drained through the relief valves to the tank, to stop the crane operation.
Tadano MKAT-40 Service Manual For Free