Hydraulics
The
hydraulics system pumps the fluid to the servo-valve, which will then activate
the actuator. A pump is located in the basement, which pumps fluid through
the system. The schematic of the pipes is as follows:
There
are two Yuken valves (DSWG-03-2B2-A120-1090) controlling the flow to the servo-valve.
The Yuken valves are two-position solenoid operated directional valves with
a spring-offset spool.
To
understand how the schematics of these valves are drawn, first look at the
valve from the front. In this position, solenoid B is on the left and solenoid
A is on the right. Since our valves are for two positions only, there is only
one solenoid operating at a time. When solenoid B is mounted (as in valve
2), the schematic for the standard mounting is to be followed. When solenoid
A is mounted (as is our valve 1), the reverse mounting schematic is the correct
one. On the schematic, the default position for these valves is the box furthest
from the solenoid since when the solenoid is activated, it pushes the spool
out (and therefore pushes the box closest to it to the active box). The active
box is the one with the labels (A,B,P,T) marked on it.
The
valve is mounted on a subplate (DSGM-03Y-2190), which connects the valve to
the hydraulic pipes. The base of the valve is labeled with 5 letters and these
correspond to the passages that connect the valve to the top of the subplate.
There are 4 holes (not five) in an inverted checkmark pattern on the top of
the subplate since one of the tank passages (T) is always blocked. These 4
holes come out of the bottom of the subplate in a diamond shaped pattern and
are not labeled so you need to see the schematic of the underside of the subplate
to see what pipes are connected to what passages. One of the holes on the
bottom of the subplate is blocked since this is a two-position valve.
Here
is a summary of what happens when each switch is turned on to operate the
actuator.
|
Switch
on |
Valve
1 |
Valve
2 |
What
the system is doing |
||
|
state |
flow |
state |
Flow
|
||
|
Pump |
default |
P
to B |
Default |
B
to T |
Circulating
the fluid from the tank back to the tank |
|
Pressure |
Solenoid
a active |
P
to A |
Default |
B
to T |
Building
up pressure in the accumulator |
|
Forward
Flow |
Solenoid
a active |
P
to A |
Solenoid
b active |
P
to B |
Pushing
fluid to the servo-valve (and actuator) |