Alternative engine cylinders are often classified as single or double acting, depending on how the working fluid acts on the piston.
A single acting cylinder in an alternate engine is a cylinder in which the working fluid acts only on one side of the piston. A single acting cylinder depends on the load, springs, other cylinders or the impulse of a flywheel, to push the piston back in the other direction. Single action cylinders are found in most types of reciprocating engines. They are almost universal in internal combustion engines (eg gasoline and diesel engines) and are also used in many external combustion engines such as Stirling engines and some steam engines. They are also found in hydraulic pumps and pistons.
A double acting cylinder is a cylinder in which the working fluid acts alternately on both sides of the piston. In order to connect the piston in a double-acting cylinder to an external mechanism, such as a crankshaft, at one end of the cylinder of the piston rod, an orifice, provided with a gland A double-acting hydraulic cylinder has a hole in the centre of the cylinder, and a double-acting hydraulic cylinder has a hole in the centre of the cylinder. Each end provided with hydraulic fluid for both retraction and piston extension A double acting cylinder is used when there is no external force to retract the piston or when a high force is required in both directions of travel.
Some Advantages of Piston Pumps
• Alternate pumps will supply High Delivery Head.
• They are self locking - It is not necessary to fill the cylinders before starting.
Some Disadvantages of Piston Pumps
• Alternating pumps provide a pulsating flow.
• Suction stroke is difficult when pumping viscous liquids.
• The production cost of piston pumps is high. This is due to the very precise sizes of cylinders and pistons. Further, the gear required to convert the rotation of the drive motor into a reciprocating action involves additional equipment and cost.
• Close-fitting moving parts cause maintenance problems, especially when the pump is handling fluids containing solids in suspension, as the particles can enter the small clearances and cause severe wear. Therefore, the piston pump should not be used for sludge.
• Provide low flow rates compared to other pump types.