5
913F Powerig® Unit (HK1191)
FIGURE 1:
The 913F uses a 2-stage pump. It will deliver
approximately 400 cubic inches per minute, or 2-1/2 gpm
at low pressure (up to about 600 psi). The high volume
low pressure stage is then automatically unloaded, and
the pump continues on the high pressure stage up to
10,000 psi with a delivery of 115 cubic inches per minute.
The pump is driven by a 5 hp 3,600 rpm Honda gas
engine, which drives the small gear “A” in the direction
shown by the arrow, which in turn drives the large gear
“B”. The wobble plate “C” of the piston pump is driven
by a coupling connected to the shaft of the larger gear.
The gear ratio is approximately 6:1, developing a speed of
about 2,000 RPM to the wobble plate “C”. Rotation of the
wobble plate imparts reciprocating motion to the pistons
“D” & “E”. In the diagram, piston “E” is starting the intake
stroke and piston “D” the pressure stroke.
Intake oil is drawn into the gear pump at “F” and trapped
between the gear teeth and the housing. It is carried
around the periphery and discharged at the outlet “G”.
Pressures up to 600 psi can be developed by the gear
pump. This low pressure oil is discharged to the outlet
check valve “U” through spool “H” of the unloading valve
and check valve “J”. Back pressure developed by forcing
the oil through the check valve provides pressure to
supercharge the piston pump. Two functions are served
by supercharging the intake “K”.
On the intake stroke, oil is forced through the intake
valve “L” to fill the pressure chamber “R”, and at the
same time, pressure forces the piston out as the wobble
plate recedes and assures contact at all times between
the pistons and the surface of the wobble plate. This
eliminates the need for springs or some other mechanical
means to retract the pistons. Piston “D” is starting the
pressure stroke. As the piston is forced into the cylinder
barrel, pressure is developed in the pressure chamber “R”.
Intake valve “L” closes and the discharge check valve “N”
is forced open, delivering oil from the piston pump to the
system which joins the oil from the gear pump at “O”.
FIGURE 2:
When the pressure builds up to the setting of the spring
“P” (Approximately 600 psi), pressure against the area
of spool “H” shifts the spool to position #2. Port “H1” of
spool “H” is uncovered, and oil is directed through the
spool to the supercharge relief valve “Q”(set at about
200 psi) or just enough to feed the high pressure pump
without cavitation and to assure that the pistons follow
the cam plate.
The excess oil from the gear pump not required to feed
the piston pump is bypassed to the reservoir at a low
pressure, reducing heat and releasing horsepower for the
development of high pressure. High pressure continues
to be developed by the piston pump and check valve “J”
forces it to flow to outlet check “U”, past the ports for
the relief valve “S” and pressure regulator fitting “T” and
finally past the outlet check poppet “W”.
When the tool trigger switch is depressed, 12 volts DC
activates the solenoid coil of the pilot valve. The pilot
valve shifts the directional valve spools. Pressurized fluid
is directed to the PULL pressure port of the installation
equipment.
When the tool trigger switch is released, the solenoid
coil is deactivated and the spring return of the pilot valve
shifts the directional valve spools. Pressurized fluid is
directed to the RETURN pressure port of the installation
equipment.
Return pressure will build up as the tool returns and
reaches the end of the stroke. When the pressure exceeds
the pressure setting of the “kick-down” relief valve, the
valve will open and fluid will pass through the return line
filter to the reservoir.
Principle of Operation
Figure 1
Figure 2
Also see Electrical and Hydraulic Schematic Diagrams on the next page.
