[Music]
welcome to the video hydraulic cylinder
speed
the speed at which the piston rod of a
hydraulic cylinder moves is based on two
factors first the size of the cylinder
bore which is the area inside the
cylinder in which the piston moves and
second the rate at which the hydraulic
fluid flows into the cylinder the
following are the customary units of
measurement in the United States
abbreviations will be used in the
calculations to determine the cylinder
speed the area of the cylinder bore is
given in inches squared the abbreviation
for area is a the flow of the fluid is
listed in gallons per minute or GPM the
abbreviation for flow is Q
the velocity of the piston rod is
measured in inches per minute the
abbreviation for velocity is V a
conversion factor is used for equations
that calculate the speed at which the
piston rod moves the constant number 231
which represents the number of cubic
inches in 1 gallon is placed in the
formula two calculations are required to
determine the extension rate of the
cylinder calculation one find the bore
size of the cylinder which is also the
piston area using the following equation
piston area equals pi times the diameter
of the piston squared divided by four
calculation to find the speed at which
the piston rod extends velocity or
extension rate of the piston rod equals
231 times the flow rate divided by the
area of the piston
what is the extension speed of the
piston rod of a cylinder with a bore
diameter of 3 inches when the hydraulic
pump produces 10 gallons per minute
step 1 calculate the piston area as
shown here
the piston area is 7.06 five inches
squared
step to calculate the extension speed as
shown here
the extension speed is 327 inches per
minute
the rate at which the piston retracts is
faster than its extension rate
the reason for the difference is that
there is less volume inside the cylinder
on the side of the piston that has the
rod 3 calculations are required to
determine the retraction rate of the
piston piston area equals pi times the
diameter of the piston squared divided
by 4 area of the rod equals pi times the
diameter of the rod squared divided by 4
velocity or retraction rate of the
piston rod equals 231 times the flow
rate divided by the difference of the
piston and rod areas
what is the retraction speed of the
piston rod of a cylinder with a bore
diameter of three inches and a rod
diameter of one inch when the hydraulic
pump produces 10 gallons per minute step
1 calculate the piston area as shown
step to calculate the rod area as shown
step 3 calculate the retraction speed as
shown
the retraction speed is 367 inches per
minute now check your knowledge by
answering these three questions pause
the video if you need more time to
answer given that the flow rate of the
hydraulic fluid from the pump is the
same
the piston rod will extend slower than
it retracts
the piston rod retracts
faster than it extends because
there is less volume of fluid to fill on
the rod side than on the other side
the number of cubic inches of hydraulic
fluid in a one gallon container
is 231
you have completed this video hydraulic
cylinder speed
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