Maxon GPSLR Series User manual

M-08-14
REV. F
APRIL 2020
© MAXON Lift Corp. 2020
MAINTENANCE MANUAL
GPSLR-33&GPSLR-44;GPSTLR-33&GPSTLR-44

TABLE OF CONTENTS
SUMMARY OF CHANGES: M-08-14, REVISION H............................................................. 4
WARNINGS........................................................................................................................... 5
SAFETY INSTRUCTIONS .................................................................................................... 6
LIFTGATE TERMINOLOGY.................................................................................................. 7
PERIODIC MAINTENANCE.................................................................................................. 9
PERIODIC MAINTENANCE CHECKS.................................................................................. 9
PERIODIC MAINTENANCE CHECKLIST........................................................................... 10
CHECKING HYDRAULIC FLUID ....................................................................................... 12
CHANGING HYDRAULIC FLUID ....................................................................................... 14
PLATFORM ADJUSTMENT................................................................................................ 16
DRIVE CHAIN ADJUSTMENT ............................................................................................ 18
DECALS.............................................................................................................................. 20
SYSTEM DIAGRAMS......................................................................................................... 24
PUMP & MOTOR SOLENOID OPERATION ...................................................................... 24
HYDRAULIC SCHEMATIC ................................................................................................. 25
ELECTRICAL SCHEMATIC................................................................................................. 26
TROUBLESHOOTING........................................................................................................ 27

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SUMMARY OF CHANGES: M-08-14, REVISION H
PAGE DESCRIPTION OF CHANGE
COVER Updated REV, date of release and cover image.
-Cover image and applicable Illustrations throughout manual are updated to show new
impact-absorbing tubes on the back of the slider frame.
-This contents of this manual applies only to GPSLR liftgates equipped with standard
control switches. All information about SmartStow controls was removed.
5 Added California Proposition 65 warning.
7 Updated terminology to show standard external control switches.
13 Added Phillips 66 Arctic Low Pour oil to table of recommended ISO-15 oils.
20 Changed Operation decal to latest decal with QR code and added decal with parts QR
code.
22 Added MAXGRIP decal for platforms with knurled surface.
23 Decal H updated to show new retention ramp.
23 Changed PRV setting to 1500 PSI on Hydraulic Schematic.

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WARNINGS
•Do not stand, or allow obstructions, under the platform when lowering the Liftgate. Be sure your
feet are clear of the Liftgate.
• Keep fingers, hands, arms, legs, and feet clear of moving Liftgate parts (and platform
edges) when operating the Liftgate.
•Disconnect Liftgate power cable from battery before repairing or servicing Liftgate.
Comply with the following WARNINGS and SAFETY INSTRUCTIONS while maintaining
Liftgates. See Operation Manual for operating safety requirements.
•If it is necessary to stand on the platform while maintaining the Liftgate, keep your feet and any
objects clear of the inboard edge of the platform. Your feet or objects on the platform can become
trapped between the platform and the Liftgate extension plate.
WARNING
!
• Correctly stow platform when not in use. Extended platforms could create a hazard for
people and vehicles passing by.
•Recommended practices for welding on steel parts are contained in the current AWS (American
Welding Society) D1.1 Structural Welding Code - Steel. Damage to Liftgate and/or vehicle, and
personal injury could result from welds that are done incorrectly.
•Recommended practices for welding on aluminum parts are contained in the current AWS
(American Welding Society) D1.2 Structural Welding Code - Aluminum. Damage to Liftgate
and/or vehicle, and personal injury could result from welds that are done incorrectly.
•Recommended practices for welding galvanized steel are contained in the current AWS (Ameri-
can Welding Society) D19.0 Welding Zinc-Coated Steel. Damage to Liftgate and/or vehicle, and
personal injury can result from welds that are done incorrectly.
Installing and maintaining a liftgate can expose you to chemicals, including lead, which are known
to the State of California to cause cancer and birth defects or other reproductive harm. To mini-
mize exposure, install and maintain liftgate in a well-ventilated area and wear proper Personal
protective equipment (PPE). For more information go to www.P65Warnings.ca.gov.
WARNING
!

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•Keep decals clean and legible. If decals are illegible or missing, replace them. Free replacement
decals are available from Maxon Customer Service.
•Consider the safety and location of bystanders and location of nearby objects when operating the
Liftgate. Stand to one side of the platform while operating the Liftgate.
•Wear appropriate safety equipment such as protective eyeglasses, faceshield and clothing while
performing maintenance on the Liftgate and handling the battery. Debris from drilling and contact
with battery acid may injure unprotected eyes and skin.
•Do not allow untrained persons to operate the Liftgate.
•Be careful working by an automotive type battery. Make sure the work area is well ventilated and
there are no flames or sparks near the battery. Never lay objects on the battery that can short the
terminals together. If battery acid gets in your eyes, immediately seek first aid. If acid gets on your
skin, immediately wash it off with soap and water.
•If an emergency situation arises (vehicle or Liftgate) while operating the Liftgate, release the con-
trol switch to stop the Liftgate.
•Read and understand the instructions in this Maintenance Manual before performing mainte-
nance on the Liftgate.
•Before operating the Liftgate, read and understand the operating instructions in Operation
Manual.
•Comply with all WARNING and instruction decals attached to the Liftgate.
•A correctly installed Liftgate operates smoothly and reasonably quiet. The only noticeable noise
during operation comes from the power unit while the platform is raised. Listen for scraping, grat-
ing and binding noises and correct the problem before continuing to operate Liftgate.
•Use only Maxon Authorized Parts for replacement parts. Provide Liftgate model and serial num-
ber information with your parts order. Order replacement parts from:
MAXON LIFT CORP. Customer Service
11921 Slauson Ave., Santa Fe Springs, CA 90670
Online: www.maxonlift.com
Express Parts Ordering: Phone [phone] ext. 4345
Email: Ask your Customer Service representative
SAFETY INSTRUCTIONS
SAFETY INSTRUCTIONS

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LIFTGATE TERMINOLOGY
INTERNAL
CONTROL SWITCH
FRAME
ASSY
POWER
PACK
HYDRAULIC
CYLINDER HYDRAULIC
LOCK
PLATFORM
FLIPOVER
DUAL RETENTION
RAMPS
TILT ARM LIFT ARM
SLIDER ASSY
(INCLUDES
MAIN BEAM)
PLATFORM
BUFFERS
SAFETY CHAIN
EXTERNAL
CONTROL
SWITCHES

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PERIODIC MAINTENANCE CHECKS
Never operate the Liftgate if parts are loose or missing.
WARNING
NOTE: Make sure vehicle is parked on level ground while performing the
maintenance checks.
Quarterly or 1250 Cycles (whichever occurs first)
Semi-annually or 2500 Cycles (whichever occurs first)
Visually check the platform hinge pins for excessive wear and broken welds. See PARTS
BREAKDOWN section for replacement parts. Also, do the Quarterly or 1250 Cycles
maintenance checks.
Check the hydraulic fluid level in the pump reservoir. Refer to the CHECKING HYDRAULIC
FLUID procedure in the PERIODIC MAINTENANCE section. Keep track of the grade of
hydraulic fluid in the pump reservoir and never mix two different grades of fluid.
If hydraulic fluid appears contaminated, refer to the CHANGING HYDRAULIC FLUID
procedure in the PERIODIC MAINTENANCE section.
Check all hoses and fittings for chafing and fluid leaks. Tighten loose fittings or replace
parts as required.
Check electrical wiring for chafing and make sure wiring connections are tight and free of
corrosion.
Check that all WARNING and instruction decals are in place. Also, make sure decals are
legible, clean and undamaged.
Check that all bolts, nuts, and roll pins are in place. Make sure roll pins protrude evenly
from both sides of hinge pin collar. Replace fasteners and roll pins if necessary.
PERIODIC MAINTENANCE
!
Check for rust and oily surfaces on Liftgate. If there is rust or oil on Liftgate, clean it off.
Touch up the paint, where bare metal is showing, with aluminum primer touchup paint.
Damaged cylinder seals and contaminated hydraulic fluid can result from paint-
ing the polished portion of the cylinder rod. To prevent damage, protect the
exposed polished portion of the cylinder rod while painting.
CAUTION
Check for debris and dirt buildup on the slider rollers and rails. Clean out any buildup of dirt
and debris.
Check that safety chain and snap hook are in place on models with no controller.
Pump EP chassis grease in each lube fitting on the cylinders and arms until grease starts
oozing from ends of the bearings. The lubrication diagram on the PERIODIC MAINTE-
NANCE CHECKLIST SHEET shows where to find the lube fittings. Wipe off excess grease
with a clean lint-free cloth.

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PERIODIC MAINTENANCE CHECKLIST
Quarterly or 1250 Cycles (whichever occurs first)
Semi-annually or 2500 Cycles (whichever occurs first)
NOTE: Make sure vehicle is parked on level ground while performing maintenance
checks.
Visually check the platform hinge pins for excessive wear and broken welds.
Do the Quarterly or 1250 Cycles Checks on this checklist.
Check the level and condition of the hydraulic fluid.
Visually check all hoses and fittings for chafing and fluid leaks. Tighten loose fittings or
replace parts as required.
Check electrical wiring for chafing and make sure wiring connections are tight and free
of corrosion. Use dielectric grease to protect electrical connections.
Check that all WARNING and instruction decals are in place. Also, make sure decals
are legible, clean, and undamaged.
Check that all bolts, nuts, and roll pins are in place. Make sure roll pins protrude evenly
from both sides of hinge pin collar. Replace fasteners and roll pins if necessary.
Check for rust and oily surfaces on Liftgate. If there is rust or oil on Liftgate or if the
Liftgate is dirty, clean it off. Touch up the paint where bare metal is showing. Refer to
the paint system CAUTION and recommended touchup paint on the preceding page.
Check for debris and dirt buildup on the slider rollers and rails. Clean out any buildup of
dirt and debris.
Check that safety chain and snap hook are in place on models with no controller.
Pump EP chassis grease in each lube fitting on the cylinders and arms until grease
starts oozing from ends of the bearings. The lubrication diagram on the PERIODIC
MAINTENANCE CHECKLIST SHEET shows where to find the lube fittings. Wipe off
excess grease with a clean lint-free cloth.

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GPSLR LUBRICATION DIAGRAM
FIG. 11-1
Refer to lubrication diagram (FIG. 11-1) to find the
lube fittings on cylinders and arms. Pump EP chassis
grease in each lube fitting on the cylinders and arms
until grease starts oozing from ends of the bearings.
Then, wipe off excess grease with a clean lint-free
cloth.
NOTE: Lube fittings are shown for the LH cylinder, lift arm, and tilt
arm. There are also lube fittings at the same places on the RH
cylinder, lift arm, and tilt arm.
LH CYLINDER,
LIFT ARM &
TILT ARM

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CHECKING HYDRAULIC FLUID
CAUTION
Keep dirt, water and other contaminants from entering the hydraulic system.
Before opening the hydraulic fluid reservoir filler cap, drain plug and hydrau-
lic lines, clean up contaminants that can get in the openings. Also, protect the
openings from accidental contamination.
+50 to +120 Degrees F - Grade ISO 32
Below +70 Degrees F - Grade ISO 15 or MIL-H-5606
NOTE: Use correct grade of hydraulic fluid for your location.
See TABLES 13-1 & 13-2 for recommended brands.
1. Unstow and lower Liftgate to ground.
UNLATCH/LATCH PUMP COVER
FIG. 12-1
4. If needed, add hydraulic fluid to the
reservoir as follows. Remove filler
cap (FIG. 12-2). Fill the reservoir with
hydraulic fluid to 3/4” above bottom
of dipstick (FIG. 12-2). Reinstall filler
cap (FIG. 12-2).
POWER UNIT FLUID LEVEL
FIG. 12-2
5. Close and latch the pump cover as
shown in FIG. 12-1.
3. Check the hydraulic fluid level in
reservoir as follows. With Liftgate on
ground, level should be as shown in
FIG. 12-2.
NOTE: If the hydraulic fluid in the
reservoir is contaminated, do
the CHANGING HYDRAULIC
FLUID procedure in this section.
PUMP COVER
LATCHES
(2 PLACES)
PUMP UNIT
(REF)
2. Unlatch and open pump cover
(FIG. 12-1).
CAUTION
Pump cover must be correctly
secured to prevent it from becom-
ing a hazard. Ensure pump cover
is latched to pump box.
FILLER CAP RESERVOIR
FLUID
LEVEL
3/4”
CAUTION
Do not fill reservoir to the FULL mark
on the dipstick. Hydraulic fluid can
overflow from the reservoir.

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TABLE 13-2
TABLE 13-1
ISO 32 HYDRAULIC OIL
RECOMMENDED
BRANDS PART NUMBER
CHEVRON HIPERSYN 32
KENDALL GOLDEN MV
SHELL TELLUS S2 VX 32
EXXONMOBIL UNIVIS N-32, DTE-24
ISO 15 OR MIL-H-5606 HYDRAULIC OIL
RECOMMENDED
BRANDS PART NUMBER
CHEVRON FLUID A, AW-MV-15
KENDALL GLACIAL BLU
SHELL TELLUS S2 VX 15
EXXONMOBIL UNIVIS HVI-13
PHILLIPS 66 ARCTIC LOW POUR
ROSEMEAD THS FLUID 17111

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CHANGING HYDRAULIC FLUID
CAUTION
Keep dirt, water and other contaminants from entering the hydraulic system.
Before opening the hydraulic fluid reservoir filler cap, drain plug and hydrau-
lic lines, clean up contaminants that can get in the openings. Also, protect the
openings from accidental contamination.
+50 to +120 Degrees F - Grade ISO 32
Below +70 Degrees F - Grade ISO 15 or MIL-H-5606
NOTE: Use correct grade of hydraulic fluid for your location.
See TABLES 13-1 & 13-2 for recommended brands.
2. Unlatch and open the pump cover
(FIG. 14-1).
3. Place empty 5 gallon bucket under drain
plug (FIG. 14-2). Remove drain plug
(FIG. 14-2). Drain hydraulic fluid. Re-
install drain plug (FIG. 14-2).
UNLATCH PUMP COVER
FIG. 14-1
POWER UNIT
FIG. 14-2
PUMP COVER
LATCHES
(2 PLACES)
PUMP UNIT
(REF)
DRAIN PLUG
1. Unstow and lower Liftgate to ground.

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POWER UNIT
FIG. 15-1
4. Remove filler cap (FIG. 15-1). Add 1
gallon of hydraulic fluid to the reservoir.
Hydraulic fluid level should be 3/4” above
bottom of dipstick (FIG. 15-1). Reinstall
filler cap (FIG. 15-1).
CAUTION
Pump cover must be correctly
secured to prevent it from becom-
ing a hazard. Ensure pump cover
is latched to pump box.
6. Close and latch the pump cover as
shown in FIG. 15-2.
5. Stow the lift and do the CHECKING
HYDRAULIC FLUID procedure in this
section of the manual.
UNLATCH PUMP COVER
FIG. 15-2
PUMP COVER
LATCHES
(2 PLACES)
PUMP UNIT
(REF)
FILLER CAP
RESERVOIR
FLUID
LEVEL
3/4”
CAUTION
Do not fill reservoir to the FULL mark
on the dipstick. Hydraulic fluid can
overflow from the reservoir.

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PLATFORM ADJUSTMENT
NOTE: Park vehicle on level ground and
unload vehicle before doing this
procedure.
1. Lower platform to ground and unfold
flipover (FIG. 16-1A).
PLATFORM LOWERED TO GROUND
FIG. 16-1A
2. Loosen adjustment and limit
bolts on both sides of platform
(FIG. 16-1B).
3. Turn adjustment bolts counter-
clockwise to tilt the tip of platform
up (FIG. 16-2), or turn clockwise
to tilt down (FIG. 16-3).
4. Once platform is adjusted, tight-
en limit bolts securely on both
sides of platform (FIG. 16-1B).
TILT ADJUSTMENT
(RH SHOWN)
FIG. 16-1B
ADJUSTMENT
BOLT
LIMIT
BOLT
RAISE TIP OF PLATFORM
FIG. 16-2
LOWER TIP OF PLATFORM
FIG. 16-3
TIP OF
PLATFORM
LEVEL LINE
TIP OF
PLATFORM
LEVEL LINE
FLIPOVER

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DRIVE CHAIN ADJUSTMENT
1. Lower the slide frame so it can be
moved out. See GPSLR/GPSTLR
Operations Manual (M-08-13).
2. Move the slide frame out (FIG. 18-1).
See GPSLR/GPSTLR Operations
Manual (M-08-13).
NOTE: Improperly adjusted drive chains
cause slide frame binding. Normal
slide frame runout speed is from 5-8
seconds.
3. Measure and record the distance from
the front edge of the plate below the
chain roller wheels, to the end of the
chain rail assembly (FIG. 18-2). Repeat
measurement for both chains.
POSITION SLIDE FRAME
FIG. 18-1
12”-18”
MEASURE DRIVE CHAIN DIMENSIONS
FIG. 18-2
CHAIN RAIL
ASSEMBLY PLATE

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4. Adjust the chain with smallest measured di-
mension, to match the chain with longest
measured dimension, as follows. Loosen chain
adjuster nut at the rear of the chain rail assem-
bly. Then, turn the front adjuster nut clockwise
to extend the shortest chain to match the longest
chain dimension (FIGS. 19-1A & 19-1B).
5. Measure the distance of the 2
chains. When dimension is the same
for both chains, tighten the adjuster
nuts (FIGS. 19-1A & 19-1B).
6. Move the slide frame in and out a few
inches and re-measure to make sure
the roller plates are even.
ADJUST DRIVE CHAINS
FIG. 19-1
FIG. 19-1A
FIG. 19-1B
FRONT
ADJUSTER
NUT
REAR
ADJUSTER
NUT

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DECALS
DECAL “B”
DECAL “F”
SERIAL PLATE (REF)
DECAL “E”
DECAL “C”
CAUTION DECAL
P/N 283989-01
CAUTION DECAL
P/N 282683-01
DECAL “A”
OPERATION DECAL
P/N 282681-01
FIG. 20-1
CAUTION DECAL
P/N 282682-01
PARTS QR CODE
DECAL
P/N 299349-02