TEMPLATE
Now that we have
the cylinder and
pump figured out...
the cylinder and
pump figured out...
...let's talk control.
More specifically,
cylinder control!
More specifically,
cylinder control!
Our cylinder has
a rod-end port,
which lets flow
in or out on the
rod side of the
cylinder...
a rod-end port,
which lets flow
in or out on the
rod side of the
cylinder...
...and a blind-end
port, which lets
flow in or out of
the blind end.
port, which lets
flow in or out of
the blind end.
When the cylinder
is moving, one port
will always have fluid
coming in, and the
other will have fluid
going out.
is moving, one port
will always have fluid
coming in, and the
other will have fluid
going out.
Which port has
the fluid going in?
the fluid going in?
It depends which
direction you want
to move the cylinder.
direction you want
to move the cylinder.
For example, fluid
coming in the rod
end and out the
blind end retracts
the cylinder.
coming in the rod
end and out the
blind end retracts
the cylinder.
Now, what's really
important is
having a way to
change the fluid
direction at will.
important is
having a way to
change the fluid
direction at will.
As well as slow
down and stop
the cylinder
if we need to.
down and stop
the cylinder
if we need to.
If you want the cylinder
to change direction we
need a way to switch
which cylinder port is
receiving flow.
to change direction we
need a way to switch
which cylinder port is
receiving flow.
And a way to cut
off flow altogether.
off flow altogether.
One valve can
do all that?
do all that?
Yep!
We'll use a 3-position
directional control
valve, or DCV for
short!
directional control
valve, or DCV for
short!
Its 3 positions
correspond to:
forward...
correspond to:
forward...
...neutral...
...and back. All
controlled by a
simple lever!
controlled by a
simple lever!
With our pump
already chosen, we
have all the info
we need to choose
a DCV.
already chosen, we
have all the info
we need to choose
a DCV.
Directional Control Valves
BM20 — $110
Flow: 3.3 gpm
Inlet Port Size: SAE 6
Pressure: 2000 psi
BM25 — $125
Flow: 6.6 gpm
Inlet Port Size: SAE 6
Pressure: 2000 psi
BM30 — $150
Flow: 7.9 gpm
Inlet Port Size: SAE 8
Pressure: 2600 psi
BM35 — $200
Flow: 9.24 gpm
Inlet Port Size: SAE 8
Pressure: 2600 psi
Things We Know:
Checklist:
Which Directional Control Valve should we choose?
Ok, we picked a
DCV. Are we
done yet?
DCV. Are we
done yet?
Almost! We just need a
relief valve and reservoir.
It's pretty quick to choose
a reservoir so let's get that
out of the way.
relief valve and reservoir.
It's pretty quick to choose
a reservoir so let's get that
out of the way.
A rule of thumb
is to choose a reservoir
that's 2.5-3 times larger
than your pump's flow
rate.
is to choose a reservoir
that's 2.5-3 times larger
than your pump's flow
rate.
Our pump's flow rate is
4.3 gallons per minute
so quick math tells me
we need a tank that's
between 10 and 13 gallons.
4.3 gallons per minute
so quick math tells me
we need a tank that's
between 10 and 13 gallons.
We want to go with
the smallest tank we
can get away with
to save money
and space.
the smallest tank we
can get away with
to save money
and space.
I remember seeing
a 12 gallon tank
in the catalogue!
a 12 gallon tank
in the catalogue!
That'll work!
It can't be
that easy.
that easy.
Sometimes it
isn't.
isn't.
If we had a large and
complex system with
lots of actuators
and accumulators, we
would need to get
detailed with the minimum
and maximum oil level.
complex system with
lots of actuators
and accumulators, we
would need to get
detailed with the minimum
and maximum oil level.
But our single-cylinder
system is pretty
simple. So we can get
by with this simple
rule of thumb.
system is pretty
simple. So we can get
by with this simple
rule of thumb.
We hope you enjoyed TEMPLATE
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