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Controlling Cylinders
In this presentation you will: identify how to control the speed and position of hydraulic
cylinders
Controlling Cylinders
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In this presentation you will explore some of the ways in which cylinders are controlled.
Needle
Controlling Cylinders
Cylinder Control - Two Positions
The pump provides a constant supply of pressurised fluid.
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A basic hydraulic circuit is shown.
When the lever is pushed forward, pressurised fluid is applied to the left side of the cylinder - the piston extends.
When the lever is pulled back, pressurised fluid is applied to the right side of the cylinder - the piston retracts to its home position.
The cylinder is controlled by a two position spool valve that has a lever actuator.
Because the valve has only two positions, the piston has only two positions - in or out.
Mechanical control
Tank
PumpSpoolvalve
Hydraulic cylinderPiston
Controlling Cylinders
1
A two position spool valve can stop a piston in any position. Is this true or false?
Answer True or False.
Question
Controlling Cylinders
Cylinder Control - Stop in Any Position
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A hydraulic system may have a requirement for a cylinder to stop in any position within its working range.
A typical application is a hydraulic lift. The operator must be able to stop the lift at any height, between its operating limits, with safe control.
A three position spool valve can be used to perform this function.
Controlling Cylinders
Stop in Any Position - Hydraulic Circuit
The pump supplies a constant supply of pressurised fluid.
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A basic hydraulic circuit is shown.
When the lever is pushed forward, pressurised fluid is applied to the left side of the cylinder. The piston extends.
When the lever is pulled back, pressurised fluid is applied to the right side of the cylinder. The piston retracts to its home position.
The cylinder is controlled bya three position spool valve that has a lever actuator.
When the lever is set to off, fluid flow to and from the cylinder ishalted, piston movement stops and the piston is locked in position.
Mechanical control
Tank
PumpSpoolvalve
Hydraulic cylinderPiston
Controlling Cylinders
2
How many positions must a spool valve have, to stop a piston in any position?
Question
A) 0
B) 1
C) 2
D) 3
Controlling Cylinders
On/Off valve starts or stops fluid flow.
Flow Control Valves to Adjust Speed
Valves control the flow of the fluid in a hydraulic system. Controlling the rate of fluid flow in a cylinder will control the speed of the piston.
Depending on the type of valve used, the fluid can be stopped and started or the speed increased or decreased. The larger the gap the larger the fluid flow.
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Adjustable Needle
Controlling Cylinders
3
A flow control valve such as a needle valve could be used to control the speed of the fluid in a hydraulic system. Is this statement true?
Answer Yes or No.
Question
Controlling Cylinders
Summary
You should now be aware of how to control cylinder:
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Speed
Position
