A cooling system will be designed so that the maximum fee on balance is calculated maximum load and over the greater part of his life can operate in several smaller load. Such changes require lower power devices, originally cruise control (when the steam driven) or in the form of bypassing the ports in the cylinder walls.
Construction of a multicylinder machines gives the possibility to change the working-working volume, taking the cylinders of the rooms with a valve-lifting mechanisms. Ring stove foot valve, which is located at the crown of the available liner can be removed by various alternative mechanical systems driven by pressure lubricating oil and controlled by solenoid valves (see Fig. 4.9). As a rule, piston rings works thrust on the head. Thus multicylinder machine (see Fig. 4.10) can have any number of cylinders unloaded for capacity reduction and, in addition, will begin unloaded increasing pressure oil pump oppressing tappets.
Fewer machines could have a valve bypass through the suction and discharge valves per cylinder, or variable clearance pocket in the head itself.
The volume can be reduced by external bypass pipeline.
Frequency of rotation of the compressor can be reduced by two-speed electric motors or electronic speed of rotation of the engine up to the lower limit is dictated by the built-in system of greasing. Many highspeed industrial machines are still driven by steam turbines and this gives the opportunity to regulate the speed of rotation within tractor.
Compressors 
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