1.12.6. Hydraulic Cylinders.

TM 5-3895-373-20 1.12.6. Hydraulic Cylinders. Several equipment motions are controlled by hydraulic cylinders. The location and description of these cylinders are as follows: a. Hopper Lift Cylinders. The hopper lift cylinders raise or lower the hopper wings to receive material from a material handling truck, or feed material into the conveyors. The hopper lift cylinders are located on each side of the hopper. The cylinders are controlled from the operator switch panel. b. Tow Point Cylinders. The tow point cylinders are used to raise or lower the leading ends of the screed tow arms to change the screed tow point. This adjustment changes the depth of the attack angle adjustment. The tow point cylinders can be controlled from switches on operator switch panel and screed control panels. Hydraulic oil to the tow point cylinder is through a manual shutoff valve and a pressure relief valve. When the tow point cylinder is not used (disconnected) and the screed tow arm pinned, the shutoff valve should be closed to prevent movement of the tow point cylinder. The relief valve allows for relief of excessive pressure from damaging the tow point cylinder should the screed run over an obstacle causing pressure on the tow point cylinder. c. Screed Lift Cylinders. The screed lift cylinders raise the screed to the travel position and lower the screed for paving. The screed lift cylinders are controlled from the operator switch panel. When in the raised position, the screed travel lock valve must be closed for safety. Closing the screed travel lock valve closes the lift cylinder bleed circuits, allowing the screed to be raised, but not lowered. The screed travel lock valve must be partially opened and screed lift switch placed in the down, FLOAT, position to lower the screed. d. Screed Extension Cylinders. The screed extension cylinders are located inside the main screed. The extension cylinders move the extension screeds in and out. This function is used to widen or narrow the width of the screed contact surface. The screed extension cylinders can be controlled from the operator switch panel and the screed control panels. 1-11