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Power unit – engine
Published in Andrew Livesey, Motorcycle Engineering, 2021
Pistons – These move up and down in the cylinder bores. This up-and-down movement is called reciprocating motion. The piston forms a gastight seal between the combustion chamber and the crankcase. The burning of the fuel and air mixture in the combustion chamber forces the piston down the cylinder to do useful work. The pistons are usually made from aluminum alloy for its lightweight and excellent heat-conducting ability. The top of the piston is called the crown; the lower part is called the skirt. The pistons must be perfectly round to give a good seal in the bore when the engine is at its normal running temperature. However, aluminum expands a lot when it is heated up. The pistons have slits in their skirts to allow for their expansion in diameter from cold to their normal operating temperature. When cold, pistons may be a slightly oval shape, so that when at running temperature they are a perfect fit in the cylinder bore.
Prototyping of automated systems
Published in Fuewen Frank Liou, Rapid Prototyping and Engineering Applications, 2019
Linear motion is the most basic of all motions. Linear motion is measured in speed, and direction. If a linear motion is used as a starting point of a system, actuators such as solenoids and cylinders are commonly used. Rotary motion is motion in a circle. If it is used as the starting point of a system, motors such as DC/AC motors, stepper motors, and servomotors are used. Rotary motion is measured in either angular velocity, the number of degrees turned in a given time, or in revolutions per minute (rpm). The direction of the turn, either clockwise or counterclockwise, is also part of the measurement of rotary motion. The strength of rotary motion is known as the torque or turning force. Reciprocating motion is back-and-forth motion. Reciprocating motion is measured by the distance between the two extremes of motion and by its cycle time. If it is used as the starting point of a system, cylinders or solenoids can be used, just like linear motion. Oscillation is the back-and-forth motion about a pivot point. It is measured in terms of both the angle of amplitude and the cycle time for one complete cycle. Oscillation tends to be an ending point for a mechanism rather than the starting point. However, some mechanisms are available to convert or transform oscillations.
Pneumatic Systems
Published in Anton H. Hehn, Fluid Power Troubleshooting, 1995
A reciprocating or piston compressor operates in the following manner. The compressor crankshaft is rotated or driven by an electric motor or other prime mover. The crankshaft and connecting rod convert this rotary motion into reciprocating motion. The piston is attached to the connecting rod by a crank pin, which permits independent movement of the piston and connecting rod. The piston is moved back and forth in the cylinder by the connecting rod and rotating crankshaft. The rod end of the cylinder is open, allowing the connecting rod to move back and forth while the piston travels in and out. The head end of the cylinder is closed and contains the intake and discharge valves (Fig. 3.2).
Comparative Investigation Into the Current-Carrying Wear Properties of Two Kinds of Carbon Skateboard/Wire Contact Under Different Conditions
Published in Tribology Transactions, 2023
Xinlong Liu, Chuanjun Tu, Yanli Liu, Gaimei Ren, Yixing Chen, Jiao Tan, Xia Huang
As shown in Fig. 2, the crank slider mechanism is driven by a servo motor and output to make a reciprocating motion. The laser sensor (Fig. 2a) is used to collect the displacement amplitude of the contact pair in real time; a DC regulated power supply is used to provide a stable current between the contact pairs. The biaxial force sensor is used to collect the contact force in the z-axis direction and the tangential force in the x-axis direction, which are used to calculate the coefficient of friction (COF) (10). A servo motor wire bar is used to maintain contact stress between the contact pairs. The voltage change in the contact interface is measured by a four-point probe (22) method; test data are collected to the PC through the NI-6210 acquisition card in real time, and the contact resistance (ECR) is calculated by Ohm’s law.