What is a common feature of hydraulic systems in farm machinery?

Hydraulic systems in farm machinery are designed to transmit power using hydraulic fluid, which is a fundamental principle of how they operate. These systems convert mechanical energy into hydraulic energy, allowing the movement and control of various equipment components more efficiently. The use of hydraulic fluid enables these systems to easily control heavy loads and perform tasks such as lifting, pushing, and pulling with minimal manual effort. Hydraulic systems capitalize on the incompressibility of liquids, allowing them to transfer force through a network of pipes and hoses with precision.

The other options do not accurately reflect the characteristics of hydraulic systems. The statement about operating without fluid overlooks the essential role that hydraulic fluid plays in the system's function. Requiring constant manual effort contradicts the efficiency and power advantages that hydraulic systems provide, as they are designed to automate and reduce the physical effort needed by operators. Lastly, the claim that hydraulic systems are not used in modern equipment does not hold true, as they are vital to a variety of contemporary agricultural machines, enhancing their effectiveness and productivity.