shock suppressors, and pressure
control valves. The low pressure side
usually contains the reservoir tank that
the pump takes suction from, heat
exchangers, and oil filters. Some
hydraulic components can be
exchanged between the two sides.
Study the diagrams shown to see how
different components of a hydraulic
system may be utilized.
There are many components that
can be used in conjunction with
hydraulics, so the following is a list of
the basic components and their general
uses with hydraulic systems. I have
included my thoughts — gathered from
years of working with hydraulics — on
their effectiveness for the Tetsujin:
This may be mandatory for
Tetsujin, since the application is to
make a portable unit that is fast. To be
portable, the power unit (pump and
motor to drive it) may have to be small
to get fast actuation; energy may have
to be stored.
Shock Suppressors: These are
basically accumulators, but their primary
purpose is to absorb shock loads that
might be introduced to the system.
Being composed of incompressible
fluid, shock loads on actuators may
cause over-pressurization of hoses or
other components. Providing a
compressible element in the system will
prevent this. Depending on the design
of the overall system, this may be
useful for the competition, but it’s hard
to tell without reviewing the design.
Hydraulic Cylinders: These are
typically used to convert hydraulic
system pressure into linear motion.
Depending on the design of the
appendages used for the lifting device,
these may be mandatory for a Tetsujin
machine. Typically, by using mechanical
advantage, cylinders can produce more
force than rotary actuators due to the
available area for the fluid pressure to
apply force upon.
Directional Control Valves:
These are used to regulate flow to
actuators or reverse the flow from one
side of an actuator to the other for
reversing the direction of a rotary
actuator or expanding and contracting
a hydraulic cylinder.
Accumulators: These devices do
what their name implies — accumulate
energy. They do this by working on the
principle of gas expansion. Ideally,
closed loop hydraulic systems work on
the principle that the liquid used is
incompressible; so, the volume you
push down a tube via the pump is the
volume that will emerge at the other
However, what if the pump you
have isn’t fast enough to get the fluid
flow you want to operate an actuator
at a fast rate? Well, in the actuator idle
time, you could still use the pump to
store energy to help push the actuator
faster when you want to use it.
Accumulators do this by having a tank
that is half-filled with the system fluid
and half-filled with a compressible gas,
like nitrogen. The idea is that the tank
system is at the system pressure of, say,
a typical 3,000 lbs, but — when an
actuator is activated and the pump
can’t make the volumetric flow rate for
the desired actuator speed — the
nitrogen will expand below the system
pressure and still supply fluid to the
actuators, at least until the accumulator
has reached its capacity.
Heat Exchangers: Hydraulic heat
exchangers are used in continuous-use
systems, where the fluid is being
constantly circulated, causing system
heat build-up. As Tetsujin machines are
not continuous-use devices, it’s likely
that the use of heat exchangers won’t
Flow Control Valves: For controlling the rate at which actuators move,
you will use a flow control valve.
Usually, they restrict the flow rate of
fluid at one of the ends of an actuator,
allowing friction to slow the fluid flow.
This may be useful for controlling the
speed at which appendages move or
matching the velocity of actuators to
move at the same rate.
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