Functional Description: 1. Hollow plunger design can be used for both pulling and pushing forces           2. Single-acting, spring retracted           3. Surface painted           4. External thread for easy installation

General hydraulic jacks are suitable for various lifting operations with low lifting heights. They consist of main components such as the oil chamber, oil pump, oil reservoir, piston, rocking handle, and oil valve. During operation, by repeatedly rocking the handle, the manual oil pump continuously pressurizes oil into the cylinder. As the oil pressure inside the cylinder increases, it forces the piston and the load above it to move upward. Opening the oil return valve allows the high-pressure oil in the cylinder to flow back into the oil reservoir, causing the load and the piston to descend together.

Special hydraulic jacks are dedicated tensioning tools used to apply tension to prestressed steel bars during the production of prestressed concrete components. Special hydraulic jacks are mostly double-acting. Common types include the through-hole type and the cone anchorage type.

The through-hole jack is suitable for tensioning bundles of steel bars or steel wires. It mainly consists of a tensioning cylinder, a compression cylinder, a compression piston, and springs. Its characteristic is that there is a through-hole channel along the axis of the tensioning machine. After the steel bars (or wires) are inserted, they are anchored by the tool anchor at the rear.

During tensioning, the front and rear oil nozzles are opened, and oil is supplied from the rear nozzle to the tensioning working oil chamber, causing the tensioning cylinder to move backward. Since the cable is anchored by the tool anchor at the top of the jack, the jack elongates the cable through the tool.

When the cable is tensioned to the required length, the rear oil nozzle is closed, and oil is supplied from the front nozzle into the compression cylinder, causing the compression piston to extend forward and press against the anchor plug. The anchor plug is then pressed into the anchor ring, thereby anchoring the cable. The rear oil nozzle is opened, and oil continues to be supplied from the front nozzle. At this point, the tensioning cylinder moves forward, and the oil in the cylinder flows back. Finally, the front oil nozzle is opened to allow the oil in the compression cylinder to flow back. The compression piston returns to its original position due to the reset spring.