Poweramp PR SERIES HYDRAULIC - Manual (Page 23)

21
OPERATION
4111-0001 — Sept. 2010
The PR dock leveler uses hydraulic logic and
one-button operation for ease of use.
The dock leveler can be operated remotely using the
RAISE button (J) on the control panel or operated
locally using the dual-lanyard pull ring (F) located in a
recess at the rear of the platform.
Platform (B) is raised by pushing and holding the
RAISE button (J) or lightly pulling and holding the
dual-lanyard pull ring (F). This activates an electric
motor (D) which, in turn, drives a hydraulic pump. The
hydraulic pump forces oil into the platform cylinder(s)
(H), causing the platform to rise. Releasing the
RAISE button (or pull ring) allows the platform to
lower.
When the platform rises to the point where there is
1 — 3 in. (25.4 — 76.2 mm) of travel left in the platform
cylinder, a cable (P) pulls valve lever (L) down. When
the cable force exceeds the force necessary to shift
the spool valve inside logic block (G), the spool shifts,
causing oil to be redirected to the lip cylinder(s) (C).
This causes the platform to stop rising and lip (A) to
extend. When the lip has fully extended, the platform
will continue to rise until it reaches the full raised
position.
Theory
The dual lanyard feature provides dual function
operation. One function raises the platform. The other
function extends the lip.
Lightly pulling dual-lanyard pull ring (F) lifts dual
lanyard lever (M), causing the contacts of dual
lanyard switch (N) to close. The closed contacts
activates electric motor (D) which causes the
platform to rise (operation is the same as when using
the RAISE button).
Releasing pull ring (F) causes lever (M) to open the
dual-lanyard switch contacts, which de-activates the
electric motor and allows the platform to lower.
When pull ring (F) is firmly pulled, the pull-ring cable
lifts lever (M), which in turn, pushes lever (L) down,
thus causing the spool valve in logic block (G) to
shift. When this happens, oil is redirected to the lip
cylinder(s), causing the platform to stop rising and
the lip to extend. This function can be used to put the
platform at the full below-dock position without fully
raising the platform.
NOTE: The ARTD switch (K) (if equipped) must be in
the OFF position for the platform to stay at
the below-dock position.
* Some models are equipped with multiple cylinders.
A — Lip
B — Platform
C — Lip Cylinder(s)*
D — Electric Motor E — Inspection Plate
F — Dual-Lanyard Pull Ring
G — Logic Block
H — Platform Cylinder(s)* J — Raise Button
K— ARTD Switch
L — Valve Lever M — Dual Lanyard Lever
N — Dual Lanyard Switch
P — Cable
C
B
D
A
E
F
K
L
M
N P
G
H
J