What is the hydraulic drive system in a tank? What is its principle? What does it do?

To control the various parts of the vehicle from the cockpit, the crew needs a system to transfer the crew's movements to the appropriate parts, which is the transmission system (for example, when you step on the gas, the transmission system transfers the force to the engine behind you). But heavy vehicles like tanks, to rely on human strength alone to manipulate certain parts, will be very strenuous or even impossible, so it will need a hydraulic booster to amplify the power of the human body, that is, the hydraulic transmission system. The principle is similar to tap water, by the engine generates force to pressurize the hydraulic fluid, and then only need to gently open the switch, a huge force will be released.