Why does the steam locomotive commutator have gear

Update:12 Jan 2021

The power handle controls the amount of intake air, while the meniscus controller controls the length of the intake air. The combination of the two controls the complete torque output.

The control of the intake air amount is called the valve; the control of the moon plate (the meniscus is wrong, the thing is on the knee) is called the handlebar. The control principle is that the sliding valve (6) is the handlebar (8) by controlling the height of the radius rod (3) on the crescent plate (1), and then forming a suitable amplitude with the combined rod (5) to control the steam chamber (6) The amplitude of the slide valve (set to A). There is an air inlet/exhaust port between the steam chamber (6) and the cylinder (7), and the air inlet/exhaust port is alternately shielded by the sliding valve to complete the steam work to the exhaust steam. The steam door is simple, that is, the amount of steam that controls the pressure steam entering the steam chamber/cylinder.

The specific motion principle is that when 8 control 3 is close to the two ends of 1 (1 can also control the commutation), the amplitude of 3 is large, the amplitude of A is large, and the reciprocating time becomes long, so the time for steam to enter the cylinder becomes longer. The amount of steam on one side of the piston increases, the pressure increases, and the force pushing the piston increases. The low speed stage is reflected in the large torque, and the high speed stage is reflected in the reciprocating motion. When the 8 control 3 is close to the middle of 1, the amplitude of 3 is small, the amplitude of A is also small, the reciprocating time is shortened, the inlet/exhaust port alternates rapidly, the steam entry time becomes shorter, and the work steam is more Quickly change from one end of the piston to the other, which will allow the piston to reciprocate more quickly, which in turn will cause the moving wheel to rotate.

The wheels of steam locomotives sometimes have to turn hard (low-speed start-up phase) and turn faster (high-speed phase). So in addition to the steam door, you need a handle.

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