SCIENCE AND TECHNOLOGY ENGLIAH FOR MECHANICAL ENGINEERING Hydraulic transmission systems efficiently transmit power farther than do mechanical systems, but not as far as electrical systems Hydraulic transmission systems may be less hazardous than electrical systems and are far safer than mechanical power transmission systems 危险的 Hydraulic oil is a good heat conductor so that the heavily loaded working area stays relatively cool. Heat generated at the working interface is conducted away rapidly. The working areas can therefore be made small because heat absorbing mass is not needed. Because of this and because of the high-pressure density, hydraulic motors weigh less than one pound per horsepower. Horsepower to weight ratios of up to 2.5 are not uncommonSCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING Hydraulic transmission systems efficiently transmit power farther than do mechanical systems, but not as far as electrical systems. Hydraulic transmission systems may be less hazardous than electrical systems and are far safer than mechanical power transmission systems. Hydraulic oil is a good heat conductor so that the heavily loaded working area stays relatively cool. Heat generated at the working interface is conducted away rapidly. The working areas can therefore be made small because heat absorbing mass is not needed. Because of this and because of the high-pressure density, hydraulic motors weigh less than one pound per horsepower. Horsepower to weight ratios of up to 2.5 are not uncommon. 危险的