WOOD'S POWR-GRIP POWER TILT Reference guide

TST-020 PT-AIR –REV. 2017-246
LEAK TEST
PROCEDURE
POWER TILT [PT] MODEL LIFTERS WITH AIR POWER SYSTEMS
TESTING AND MAINTENANCE MUST BE
DONE BY A QUALIFIED PERSON
KEEP FOR FUTURE REFERENCE

TST-020 PT-AIR –REV. 2017-246

TST-020 PT-AIR –REV. 2017-246
TABLE OF CONTENTS
LEAK DETECTION
SYMPTOMS OF VACUUM LEAK 1
DETERMINING LEAK EXISTENCE 1
ADDRESSING LEAK 1
BASIC REPAIR TIPS 2
PRELIMINARY TEST 3
VACUUM GENERATING SYSTEM TEST 4
PAD SYSTEM TESTS 8
SYSTEM CONFIRMATION 10
DIAGNOSTICS
AIR POWERED PUMP [VENTURI] DIAGNOSIS 11
ACTUATOR TILTS AFTER STOPPING 12
ADDITIONAL INFORMATION 14

TST-020 PT-AIR –REV. 2017-246 Page 1 of 14
SYMPTOMS OF VACUUM LEAK
A severe leak is evidenced by a lifter’s inability to draw full vacuum while attached to a clean,
smooth, nonporous surface. In such cases, the vacuum level shown on the vacuum gauges will be
less than 16" Hg [-54 kPa], the red zone of the vacuum gauge.
A moderate leak is indicated if the lifter loses more than 4" Hg [-13.5 kPa] in 5 minutes during a
vacuum test when the power is off. This amount of lost air is serious enough to warrant repairing
the lifter’s vacuum system.
DETERMINING LEAK EXISTENCE
To determine if lifter has a vacuum leak, perform the Vacuum Test as described in the Maintenance
section of lifter’s instruction manual.
During vacuum test it is recommended that you take notes on amount of air lost in time increments
(i.e. “Lost 5" Hg [-17 kPa] in 5 minutes”). This assists in diagnosing the location of the leak because
there may be more than one component leaking vacuum. For example, if an isolated section tests
positive for a leak but the leak rate is less than that of the whole lifter, then there is still one or more
vacuum leak elsewhere in the system.
ADDRESSING LEAK
If the leak is sufficient to warrant repair:
Locate the cause of leak beginning by inspecting the vacuum pads, fittings and hoses of the entire
vacuum system. Look for contamination, cuts or abrasions on pad faces, cracks in the pad suction
stem, cracks, abrasions or cuts in hoses, damaged fittings and loose hoses at connection points.
If leak is severe, the cause is often a visibly damaged part.
Caution: Do not apply soapy water to fittings or vacuum hoses in an attempt to find leaks, since it
will only be drawn inside the vacuum system.
If the leak’s source is not immediately evident, the various sections of the entire vacuum system
must be systematically isolated and tested to determine the leakage point. The process to
accomplish this is described in the tests to follow.
Note: The information gathered when performing a vacuum test is only valid if the tools used to
perform the test are accurate. Be sure that the tools used are capable of completely sealing the
isolated parts of the vacuum system when tested.
Recommended tools
1
: Plugs for hoses and fittings, ball valve with vacuum gauge attached,
appropriate hose adapters and extra vacuum hose.
2
1
If needed, test equipment is available from Wood’s Powr-Grip. Contact us for additional information.
2
Procedure assumes operator has access to appropriate tools

TST-020 PT-AIR –REV. 2017-246 Page 2 of 14
BASIC REPAIR TIPS
1) When removing a hose from a barbed fitting, avoid damaging the barbs of the fitting to which
the hose is attached. Cuts or nicks in fitting barbs can create a leak that did not previously
exist.
2) If a hose is removed from a barbed fitting, cut approximately 1/8" to 1/4" [3 to 6 mm] off the
end of the hose before reinstalling it on the fitting, in order to remove damaged hose ends.
Note: In release mode, the vacuum system of this lifter provides quick release using a “blow off”
feature, where air is pumped into the pad system for faster load release. When testing for leaks, it
is often necessary to seal off the system by capping off, plugging fittings and lines, or closing all
pad shut-offs. Due to this, the use of the release function is not recommended during the
repair process. Release mode will cause pressure to build in the sealed off section and may
damage components.
3) To release the lifter when testing with capped or closed off sections: Remove or open the item
used to close off the vacuum system. Do not use the lifter’s release mode.

TST-020 PT-AIR –REV. 2017-246 Page 3 of 14
PRELIMINARY TEST
Note: The following assumes operator has access to suitable plugs to seal off the section being
tested.
This test determines whether leakage is located in the vacuum generating system or the pad
system.
1) Remove the hose from the vacuum filter that attaches to the
vacuum pad system. Using a cap plug (1A) cap off the fitting
of the vacuum filter as shown in FIGURE 1.
Note: The size plug needed may vary with lifter model.
2) Repeat the vacuum test with the filter capped-off.
If the vacuum level of the lifter’s vacuum gauge holds
steady and does not drop, this indicates that the leak is
located in the vacuum pad system between the filter and
vacuum pads.
Proceed to Pad System Tests.
If the vacuum level of the lifter’s vacuum gauge starts
and continues to drop, this indicates that the leak is
located in the vacuum generating system.
Proceed to Vacuum Generating System Test.
FIGURE 1
1A

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VACUUM GENERATING SYSTEM TEST
Note: The following assumes operator has access to suitable plugs, a
ball valve with vacuum gauge, and additional hose and adapter fittings
for connecting the ball valve to the lifter’s vacuum lines and fittings.
The most likely leak points in the vacuum generating system are the
check valve, the filter, or the control valve. Leave the filter disconnected
(capped-off) from the pad system and test:
1) Isolate the check valve from the system.
The check valve (2A) is attached to the venturi assembly.
See FIGURE 2.
2) Remove the hose (2B) from the venturi assembly connected to the
fitting with the check valve.
Using the ball with vacuum gauge and appropriate hose adapters,
attach the ball valve (end with vacuum gauge attached) to the
fitting where the hose was removed. Attach the other end of the
ball valve to the hose that was removed from the fitting.
See FIGURE 3. 3) With ball valve in the open position (handle in-line
with valve), apply vacuum. When a sufficient level
of vacuum is reached, close the ball valve (turn
handle perpendicular to the valve) and close the air
supply valve to the venture air pump.
4) Observe both the lifter’s and ball valve’s vacuum
gauges:
If the vacuum level of the lifter’s vacuum gauge
starts and continues to drop, a leak is located in
either the vacuum filter or control valve assembly.
Proceed to step 5.
If the vacuum level of the ball valve’s vacuum
gauge starts and continues to drop, or if both the
vacuum gauges hold steady and do not drop, this
indicates that the check valve leaks.
Note: The check valve may leak intermittently, so
if both vacuum gauges hold steady and do not
drop, the check valve is indicated as the cause.
If the ball valve’s vacuum gauge did drop and
indicates a leak: Check the attached fittings and
line connecting to the vacuum tank for loose
connections or indication of damage or cracks to
the fittings or lines. If there is no visible damage
or neither vacuum gauge indicates a leak during
the test, replace the check valve.
FIGURE 2
2A
2B
FIGURE 3

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If the vacuum level of both the lifter and ball valve’s vacuum gauges start and continue to
drop: The check valve leaks and needs to be replaced and there is a leak located in either
the filter or control valve assembly.
First, replace the check valve then proceed to step 5.
5) If it is determined that a leak exists in either
the filter or control valve assembly: Remove
the ball valve from the hose and reinstall it so
that the vacuum gauge is now in the line
connected to the control valve.
6) Remove the hose that connects the control
valve to the vacuum filter and cap off the
fitting (4A). See FIGURE 4.
7) With the ball valve in the open position
(handle in-line with the valve), apply vacuum.
When a sufficient level of vacuum is reached,
close the ball valve (turn handle
perpendicular to the valve) and close the air
supply valve to the venturi pump.
8) Observe the ball valve’s vacuum gauge:
If the vacuum level of the ball valve’s
vacuum gauge starts and continues to
drop: The control valve assembly is the source of the leak.
Examine the hose connection to the control valve and the fittings for any indications of loose
connections, cracks or damage. If there is no visible damage, replace the control valve.
If the vacuum level of the ball valve’s vacuum gauge holds steady and does not drop: The
vacuum filter is the cause.
Proceed to step 9.
FIGURE 4
4A

TST-020 PT-AIR –REV. 2017-246 Page 6 of 14
9) To individually test the filter, leave the ball valve
connected to the venturi pump. Connect the end of the
ball valve connected to the control valve directly to the
hose of the vacuum filter assembly.
Cap off the fitting of the filter that was connected to the
vacuum pads if it is not capped-off. See FIGURE 5.
10) Move the handle of the control valve to the apply
position and open the air supply valve.
11) When a sufficient level of vacuum is reached, close the
ball valve and the air supply valve.
12) Observe the lifter’s vacuum gauge:
Based on the previous tests it is expected that the
vacuum level of the lifter’s vacuum gauge will start
and continue to drop, verifying that the vacuum filter
assembly does leak.
If confirmed, examine the hose connection to the
vacuum filter and the fittings for any indications of
loose connections, cracks or damage.
The twist drain plug located at the base of the filter
bowl should never be used when the filter is used on
a vacuum system.
Verify that the drain plug is tight and has not been
used. If the twist drain has been used it will need to
be removed and cleaned before reinstalling.
oRemove the filter bowl from the filter and remove
the plastic nut that attaches the drain plug to the
filter bowl.
oRemove the drain plug and the O-ring located in
the bottom of the filter bowl.
oClean out the bottom of the filter bowl where the
O-ring is located.
oClean the O-ring and apply a light film of rubber compatible grease.
oReinstall the drain plug and secure it with the retaining nut.
Note: Do not over-tighten the retaining nut; this is a plastic nut and part. It is the O-ring that
creates the seal to the bowl.
Service the filter according to the lifter’s maintenance instructions, giving particular attention to the
O-ring located between the filter bowl and body.
Re-test the filter assembly.
If the leak continues, replace the filter.
Repair or replace any parts identified to leak and repeat the Preliminary Test.
FIGURE 5

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Once the vacuum generating system is confirmed to hold (no significant leaks noted per the
vacuum readings), re-connect the pad system, proceed to system confirmation and retest the
vacuum system as described.

TST-020 PT-AIR –REV. 2017-246 Page 8 of 14
PAD SYSTEM TESTS
Note: The following assumes operator has access to suitable plugs, a ball valve with vacuum
gauge, and additional hose and adapter fittings for connecting the ball valve to the lifter’s vacuum
lines and fittings.
If it was determined that the vacuum generating system does not leak, or if any existing leaks in the
vacuum generating system have been repaired, proceed with the following:
Isolate the vacuum pads, fittings and vacuum line sections until the leak point can be located:
Lifter models with shut-off valves on all vacuum pads:
1) Close the shut-off valve to all the vacuum pads.
Two shut-off valves are attached to
the central manifold and the
remaining shut-off valves are located
in the pad lines to the individual
vacuum pads. (See FIGURE 6.)
2) Repeat the vacuum test.
If the vacuum level of the lifter’s
vacuum gauge holds steady and
does not drop: The vacuum pad
system does not leak between
the vacuum filter and the shut-off
valves.
Proceed to step 3.
If the vacuum level of the ball valve’s vacuum gauge starts and continues to drop: A leak
does exist between the vacuum filter and the shut-off valves.
oExamine the hoses, hose connections and fittings for any indication of loose
connections, cuts or abrasions, cracked or damaged fittings. If there is no visible
damage, use the ball valve with gauge and/or cap plugs to cap off individual fittings and
lines to determine where the leak is.
See step 6 for more information on this process.
For lifter models without shut-off valves or if it was
determined that there is no leak up to the shut-off
valves:
3) Remove the pad fitting from each of the vacuum pads.
Cap off the pad fittings.
See circled detail in FIGURE 7.
4) Open the air supply valve and apply the lifter.
FIGURE 6
FIGURE 7

TST-020 PT-AIR –REV. 2017-246 Page 9 of 14
5) Observe the vacuum gauge.
If the vacuum level of the lifter’s vacuum gauge holds steady and does not drop: The leak is
located in one or more of the vacuum pads.
Re-attach one pad at a time to determine which vacuum pads are leaking. Repair or
replace as needed.
If the vacuum level of the lifter’s vacuum gauge starts and continues to drop: Either a leak
exists between the pad fittings and the filter or if the lifter has shut-off valves to all the pads
and step 2 determined that the lifter does not leak up to the shut-off valves, then the leak is
located between the pad fittings and the shut-off valves.
Proceed to step 6.
6) The ball valve with gauge and/or cap plugs can be used to test individual lines, sections, fittings
or parts.
In FIGURE 8, caps are used to cap individual sections where, in the first two views, a tee fitting
and a shut-off valve are shown capped-off. Vacuum is then applied so the line up to the
capped off section will be tested. If the leak is no longer present, it indicates that the leak is in
the section past the capped-off part or, if the leak continues, that the leak is between the
capped-off part and the filter.
In the right view, caps were used to seal off four pad lines at the manifold.
7) Check individual fittings and parts by attaching the
ball valve to any active vacuum line (see FIGURE 9,
where a tee fitting has been removed from its line and
attached directly to the ball valve.) After vacuum is
applied, the ball valve is closed so the only part being
tested is the tee fitting itself. A drop in vacuum on the
ball valve’s vacuum gauge indicates that the tee
fitting leaks. If the vacuum level holds steady and
does not drop the tee fitting does not leak.
This process can be used to test any individual
part, assembly, or section.
Once all leaks have been identified and repaired, proceed to System Confirmation and retest the
vacuum system.
FIGURE 8
FIGURE 9

TST-020 PT-AIR –REV. 2017-246 Page 10 of 14
SYSTEM CONFIRMATION
Once all leaks have been identified and repaired, reassemble all parts of the lifter.
A vacuum test, as described in the instruction manual, should be performed following any repair or
service to a vacuum lifter.
Note: If system is equipped with shut-offs or quick connects, a vacuum test should be performed
with these parts in every manner of use (i.e. shut-off valves should be tested in both the open and
closed position, quick connect valves should be tested both when connected and disconnected).
All parts must be verified in relation to their function and the lifter must pass all vacuum tests before
returning to operation.

TST-020 PT-AIR –REV. 2017-246 Page 11 of 14
DIAGNOSTICS
VENTURI AIR POWERED PUMP DIAGNOSIS:
A problem with the venturi air pump is indicated when the lifter cannot attain sufficient vacuum (>16"
Hg [54 kPa]) but does not leak when a vacuum test is performed.
Requirements:
The power requirements of the venturi is designated by a pressure rating (in psi or kPa) and a flow
rating (in SCFM or liters/minute). This information is located on the serial number label and in the
specifications of the lifter’s instruction manual.
Verify that compressor can provide a continuous flow at the required pressure.
Note: Compressor must be of a capacity that will provide the required air flow and pressure to the
lifter even if there are other demands on the compressor (e.g. if there are other demands for
compressed air, the compressor must be of a size that can meet those demands and still supply the
lifter’s power requirement).
Setting the pressure:
Attach the airline to the air pressure regulator of the lifter.
Open the air supply valve. Note: The type valve may vary with lifter
model and age.
Place the control valve in the APPLY position: Pull up on the control
valve lever and move it forward, to the APPLY position (see FIGURE
10). Verify that the regulator pressure is set to a minimum of 80 psi
when running (80 to 90 psi typical operating pressure). If lower than
80 psi, increase the pressure to the lifter.
To set the regulator: Pull up on the yellow locking cap of
the regulator and turn clockwise to increase the
pressure reading on the gauge. (See FIGURE 11.)
FIGURE 10
FIGURE 11

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Perform a vacuum test.
If the vacuum level still does not reach a sufficient level
(>16" Hg. [54 kPa]) remove the muffler (unscrew
counter-clockwise) from the venturi assembly to
determine if a restriction exists. (See FIGURE 12.)
Repeat the vacuum test.
If the lifter does pull sufficient vacuum (> 16" Hg. [54
kPa]) replace the muffler.
If the lifter still does not pull sufficient vacuum replace
the venturi.
ACTUATOR TILTS AFTER STOPPING:
If, when tilted to a position, the actuator continues to move or begins to move back towards its
original position, the issue will typically be with the tilt control valve or the flow valves mounted to the
actuator. The exception to this would be if the internal seals of the actuator have worn to the point of
leaking across the seals.
The flow valves (12A and 12B)are mounted directly to the actuator
ports. The flow valves should be checked first.
The flow valves may leak past the seals that allow the valves to
pivot. When this happens, air can typically be felt along the
seams of the collar/body of the flow valve. With the air supply
valve open, tilt the lifter to the position where it drifts and check to
see if air can be felt leaking around the body of the flow valve.
Note: If the drift causes actuator to retract (pad frame moving to
flat position) the upper flow valve is indicated. If the drift causes
actuator to extend (pad frame moving to vertical position) the
lower flow valve is indicated.
Since this is a pressure port, a soap and water solution can be
used to check for leaks. Spray a small amount of soapy water
around the flow valve that is indicated by the direction of the drift.
Bubbles will indicate a leak.
Replace any flow valve determined to leak.
If it is determined that the flow valves are not the cause, the tilt
control valve (12C) should be checked.
FIGURE 12
FIGURE 12
12B
12A
12C

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The tilt control valve consists of an incoming airline (13A),
two vent plugs (13B) and two feed lines (13C).
When the handle is in the center position, all the ports are
closed.
A leak is indicated when the handle is in the center and air
is flowing from the vent ports or from the ports to the feed
lines of the actuator.
Begin by checking the ports with the vent plugs (13B).
With the air supply valve open, tilt the lifter to the position
where it drifts and lightly spray the vent plugs with a soap
and water solution. Bubbles indicate a leak.
If there is no indication of a leak at the vent plugs, the
feed lines to the actuator should be checked.
To check the actuator feed line ports:
Disconnect the air supply from the lifter.
Disconnect the hoses from the tilt control
valve that connect to the flow valves of the
actuator.
Reconnect the air supply to the lifter.
Note: Do not engage the handle of the tilt valve
assembly with the hoses removed.
Wrap a smooth towel (14A) tight over the end of
either of the ports that connect to the actuator.
Spray the area covering the open port with a soap
and water solution. Bubbles indicate a leak. If there is no leak when the first port is tested, test the
second port.
If there is any indication of a leak through either port of the tilt control valve, replace the valve.
If neither the flow valves nor the tilt control valve leak, the issue is likely to be the internal seals of
the actuator. Contact Wood’s Powr-Grip for additional information.
FIGURE 13
13A
13B
13C
FIGURE 14
14A

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ADDITIONAL INFORMATION
1) When requesting information on a particular lifter, please have the model number and
serial number available.
2) CAUTION: Always proceed with caution when opening enclosures containing electrical
wiring. Wiring is often connected to components in the cover, as well as the enclosure
itself.
3) In some cases a leak may be identified in an assembly (such as a filter or valve assembly)
but the actual cause is not apparent (neither the filter nor the valve itself are the cause). In
these cases, the leak may be caused by a cracked fitting. Cracks in fittings may be visible
but are often virtually impossible to locate except under factory test conditions. They may
appear as dark lines along the seam of female fittings, along the hex nut section of female
hose nipples, or at the base of the threads on male fittings. If a leak is traced to an
assembly and the cause is not visibly apparent, it may be best to simply replace the whole
assembly rather than a single component.
4) If any metal fittings are disassembled during testing, always apply thread sealant (Teflon
tape or similar product) to the male threads prior to reassembly, in order to avoid vacuum
leaks.
For plastic fittings use only Teflon tape. Liquid or paste sealants must not be used
because they may damage plastic parts.
5) When assembling fittings, do not over-tighten. After first applying adequate thread sealant
or tape, the fitting should be finger-tightened as much as possible.
A straight fitting should be tightened no more than two additional revolutions with a wrench.
An elbow fitting should be tightened no more than one and one-half additional revolutions
with a wrench.
Once an elbow or tee fitting is tightened with a wrench, the fitting should be aligned
clockwise with a wrench
6) Please note: The information that is gathered when performing a vacuum test is only valid
if the tools used to perform the test are accurate. Be sure that the tools you use are
capable of completely sealing your system.
If needed, test equipment is available from Wood’s Powr-Grip Co.
For further suggestions or information, please contact our staff at:
Wood’s Powr-Grip Co., Inc.
908 West Main
Laurel, Montana 59044
800.548.7341
406.628.8231
406.682.8354 (fax)
www.WPG.com
ALL LIFTERS MUST BE TESTED AFTER MAINTENANCE
SEE INSTRUCTION MANUAL