Maxon DMD-22 User manual

© MAXON Lift Corp. 2022
M-21-01
SEPTEMBER 2022
To fi nd maintenance & parts information for your Tool Truck DMD Liftgate, go to www.maxonlift.
com. Click the PRODUCTS, RAILIFT & DMD buttons. Open the Maintenance Manual in the
PRODUCT DOCUMENTATION window. For parts, click on the PARTS PORTAL, RAILIFT &
DMD buttons.

TABLE OF CONTENTS
WARNINGS ........................................................................................................................... 3
NOTICE ................................................................................................................................. 4
VEHICLE REQUIREMENTS ................................................................................................. 5
BODY STRENGTH ................................................................................................................ 5
INSTALLED LIFTGATE ......................................................................................................... 7
LIFTGATE INSTALLATION COMPONENTS ........................................................................ 9
INSTALLATION & MANUALS KITS ................................................................................... 10
STEP 1 - POSITION LIFTGATE ..........................................................................................11
BOLTING LIFTGATE TO BODY ...........................................................................................11
STEP 2 - RUN POWER & GROUND CABLES ................................................................... 12
STEP 3 - CONNECT POWER CABLE ................................................................................ 13
STEP 4 - CONNECT GROUND CABLE ............................................................................. 15
STEP 5 - PRESSURIZE HYDRAULIC SYSTEM ................................................................ 18
STEP 6 - CHECKING HYDRAULIC FLUID ......................................................................... 19
STEP 7 - CONNECTING TAILIGHTS .................................................................................. 21
STEP 8 - REMOVE UPPER SUPPORT FIXTURE ............................................................ 22
DECALS .............................................................................................................................. 23
DECALS & PLATES ........................................................................................................... 25
SYSTEM DIAGRAMS ......................................................................................................... 26
PUMP MOTOR & VALVE OPERATION .............................................................................. 26
HYDRAULIC SCHEMATIC .................................................................................................. 27
ELECTRICAL SCHEMATIC ................................................................................................. 28
ELECTRICAL SCHEMATIC (ABOVE BED MODEL) ........................................................... 29
ELECTRICAL SCHEMATIC - JUMPER HARNESS ASSEMBLY ........................................ 30
DMD ELECTRICAL VALUES & TORQUE VALUES ............................................................ 31
PRE-DELIVERY INSPECTION FORM ................................................................................ 32

3
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
• Do not stand, or allow obstructions, under the platform when lowering the Liftgate. Be sure your
feet are clear of the Liftgate.
• Keep fi ngers, hands, arms, legs, and feet clear of moving Liftgate parts (and platform
edges) when operating the Liftgate.
• Make sure vehicle battery power is disconnected while installing Liftgate. Connect vehicle
battery power to the Liftgate only when installation is complete or as required in the installation
instructions.
• If it is necessary to stand on the platform while operating 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.
• Never perform unauthorized modifi cations on the Liftgate. Modifi cations may result in early failure
of the Liftgate and may create hazards for Liftgate operators and maintainers.
• 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 can 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.
WARNING
!
WARNINGS
Comply with the following WARNINGS and SAFETY INSTRUCTIONS while installing
Liftgates. See Operation Manual for operating safety requirements.
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
!

4
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
SAFETY INSTRUCTIONS
• Comply with all WARNING and instruction decals attached to the Liftgate.
• 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 fl ames 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 fi rst 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 Installation Manual before installing Liftgate.
• Before operating the Liftgate, read and understand the operating instructions in Operation
Manual.
• 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 and lowered. Listen for
scraping, grating and binding noises and correct the problem before continuing to operate Liftgate.
NOTICE NOTICE
• Maxon Lift is responsible for the instructions to correctly install MAXON Liftgates on
trucks only.
• Liftgate installers, not Maxon Lift, are responsible for reviewing and complying with all
applicable Federal, State, and Local regulations pertaining to the truck.

5
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
VEHICLE REQUIREMENTS
The DMD is a body-mounted Liftgate
that puts forces on the side walls of truck
bodies (FIG. 5-1). For correct installa-
tion, truck bodies must be strong enough
to withstand the tension, compression
and shear forces shown in FIG. 5-1. Use
TABLE 5-1 to determine the forces that
apply to your Liftgate.
X= Tension on each sidewall
Y= Compression on each sidewall
Z= Shear on each sidewall
X
BED HEIGHT
Z
NOTE: Maximum Operating Bed Height (Unloaded) for body varies depending on
platform. Refer to TABLE 5-1. Minimum Bed Height is 30” (Loaded). Do not
install this Liftgate on vehicle bodies equipped with swing open doors.
Consult truck body manufacturer for truck body strength data. Make sure the
forces created by the Liftgate are within the limits prescribed by the truck body
manufacturer.
WARNING
FIG. 5-1
BODY STRENGTH
NOTE: Installer is responsible for ensuring vehicle meets Federal, State, and Local
standards and regulations.
!
Y
64-13/16”
TABLE 5-1
DMD-22 FORCES 99” WIDE 102” WIDE
MODEL CAPACITY P/F SIZE (X) (Y) LB (Z) LB (X) (Y) LB (Z) LB
2200 LB 72” 1103 3098 1117 3136

6
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
VEHICLE REQUIREMENTS - Continued
NOTE: Dimensions are provided as reference for fi tting Liftgate to body.
NOTE: Make sure vehicle is parked on level ground while preparing ve-
hicle and installing Liftgate.
1. Check for correct clearances (FIGS. 6-1 and
6-2) on vehicle to prevent interference be-
tween vehicle and Liftgate. Refer to FIG. 6-1
for a standard installation. See FIG. 6-2 and
TABLE 6-1 for above bed options.
PLATFORM
GROUND
VEHICLE
FLOOR
STANDARD DMD
FIG. 6-1
ABOVE BED TRAVEL “A” 1-1/4”
(102” PLATFORM)
3-1/2”
(99” PLATFORM)
MAX BED HEIGHT “BH” 52-3/4” 50-1/2”
COLUMN HEIGHT ABOVE BED “C” 59-1/2” 59-1/2”
DMD ABOVE BED OPTIONS
TABLE 6-1
DMD ABOVE BED OPTIONS
FIG. 6-2
59-1/2”
17”
54” MAX BED
HEIGHT
VEHICLE
FLOOR
“A” ABOVE
BED TRAVEL
15-1/2”
“C”
“BH” MAX
BED HEIGHT
GROUND
PLATFORM

7
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
1. With the vehicle parked on
level ground, the columns of
the DMD must be perpendicu-
lar to the ground (vertical) for
the Liftgate to operate correctly
(FIG. 7-1).
INSTALLED LIFTGATE
LIFTGATE INSTALLED ON TRUCK BODY
(COLUMNS SHOWN PERPENDICULAR TO LEVEL GROUND)
FIG. 7-1
LEVEL
VEHICLE REQUIREMENTS - Continued
91° MAX.
NOTE: If Liftgate columns exceed a 91 degree angle from level ground when
installed on body, or if columns cannot be mounted fl ush against rear of
vehicle, a steel fi ller may be used to bridge gap between vehicle body
and Liftgate columns. Make sure the added materials and welds meet the
BODY STRENGTH requirements shown on the previous pages.

8
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
VEHICLE REQUIREMENTS - Continued
2. With Liftgate centered on vehicle body, each column
should fi t on the corner posts of vehicle body with
little or no off set (FIG. 8-1). Some off set from corner
posts is allowed on the inboard side of the columns.
Liftgate in stow position extends behind vehicle
body as shown in FIG. 8-1A.
LIFTGATE COLUMNS FITTED TO BODY CORNER
POSTS WITH LITTLE OR NO OFFSET
FIG. 8-1
“W”
88-3/8” (FOR 99” W VEHICLE)
91-3/8” (FOR 102” W VEHICLE)
VEHICLE BODY
CORNER POST
(2 PLACES)
LH
COLUMN
RH
COLUMN
FIG. 8-1A
14-3/4”
LIFTGATE
(RH VIEW)

9
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
LIFTGATE INSTALLATION COMPONENTS
TOOL TRUCK DMD & PARTS KIT
FIG. 9-1
LIFTGATE
ELECTRICAL
PARTS KIT
NOTE: Make sure you have components and parts before you start installing Liftgate.
Compare parts in the part box and each kit box with packing list enclosed in
each box. If parts and components are missing or incorrect, call:
Maxon Customer Service
Call [phone] or
Send e-mail to [email protected]

10
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
To fi nd maintenance & parts information for your DMD Liftgate, go to www.maxonlift.
com. Click the PRODUCTS, RAILIFT & DMD buttons. Open the Maintenance Manual
in the PRODUCT DOCUMENTATION window. For parts, click on the PARTS PORTAL,
RAILIFT & DMD buttons.
INSTALLATION & MANUALS KITS
ITEM NOMENCLATURE OR DESCRIPTION QTY PART NUMBER
REF DMD ELECTRICAL PARTS KIT 1 298882-11-100
1HEAT SHRINK TUBING, 3/4” X 1-1/4” LG. 1 253316-04
2HEAT SHRINK TUBING, 1” X 1-1/2” LG. 2 907169-01
3STARTER SOLENOID, 12VDC 1 297271-01
4HEX BOLT, 1/4”-20 X 1” LG. 2 903107-03
5COPPER LUG, 2 GA, 5/16” 2 906497-02
6CABLE ASSEMBLY, 2 GA, RED, 3/8”, 1/4” RING, 24” LG. 1 212675-24
7CABLE ASSEMBLY, 2 GA, RED, 1/4” RING, 35’ LG. 1 212676-35
8CABLE ASSEMBLY, 2 GA, BLACK, 3/8” RING, 35’ LG. 1 212677-35
9HEX HEAD NUT, 1/4”-20 2 903107-3
10 FLAT WASHER, 1/4” 2 903412-01
11 LOCK WASHER, 1/2” O.D. X 1/4” I.D. 2 902019-3
12 SPRING CLIP 8 050079
13 CIRCUIT BREAKER, 150 AMP 1 907207-02
14 2-BUTTON CONTROL PENDANT, GRAVITY DOWN 1 212516-01
TABLE 10-1
TABLE 10-2
ITEM NOMENCLATURE OR DESCRIPTION QTY PART NUMBER
REF DMD MANUALS KIT 1 298884-11
1INSTALLATION MANUAL 1 M-21-01
2OPERATION MANUAL 1 M-21-02
3DECAL, MAXON 24/7 SUPPORT 1 298634-01

11
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
STEP 1 - POSITION LIFTGATE
BOLTING LIFTGATE TO BODY
1. Use correct jig to drill holes in vehicle
body.
POSITIONING LIFTGATE & BOLTING ON VEHICLE BODY
FIG. 11-1
2. Hoist liftgate by the installation support
in position on the back of vehicle body
(FIG.11-1). Next, align holes in the mount-
ing fl anges on the columns with bolt holes
drilled in the corner posts on the vehicle
body (FIG.11-1). Then, bolt Liftgate to ve-
hicle body with mounting bolts provided by
vehicle OEM (FIG. 11-1). Torque mounting
bolts to OEM specifi cations.
HOIST CHAIN
OEM
MOUNTING
BOLTS
INSTALLATION
SUPPORT

12
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
STEP 2 - RUN POWER & GROUND CABLES
Never route an energized wire. Make sure the vehicle battery is disconnected.
Always route electrical wires clear of moving parts, brake lines, sharp edges and
exhaust systems. Keep power and ground wires separated. Avoid making sharp
bends in wiring. Attach securely. If drilling is necessary, fi rst check behind the
drilling surface to prevent damage to any fuel lines, vent lines, brake lines or wires.
CAUTION
!
NOTE: Ensure the lug end of each cable is inserted in the battery box on vehicle, but
not connected. The end of each cable must be long enough to reach the power
(+) and ground (-) terminal connections in battery box and Liftgate power unit in
main housing without straining the cable connections.
1. Run the 35” power (+) cable and ground (-) cable (Kit items) along
vehicle frame from vehicle battery box to Liftgate at rear of vehicle.
Place lug end of power cable nearest the vehicle battery. Clip (Kit
item) power (+) cable and ground (-) cable to vehicle frame at inter-
vals shown in FIG. 12-1. Keep enough length of each cable to reach
positive (+) and negative (-) terminals without straining cables when
connected. Use plastic ties (Kit items) where needed.
35’ BLACK
GROUND
(-) CABLE
35’ RED
POWER (+)
CABLE
150 AMP
CIRCUIT
BREAKER
ROUTING POWER & GROUND CABLES FROM BATTERY BOX TO LIFTGATE
FIG. 12-1
VEHICLE
FRAME
FRONT OF VEHICLE
REAR OF VEHICLE
FRAME
CLIPS
18” - 24”
SPACING
24” RED POWER
(+) CABLE TO
VEHICLE BATTERY
2. Connect power (+) cable to AUX stud on 150
amp circuit breaker (Kit item), and 24” power (+)
cable (Kit item) to the BAT stud on circuit breaker.
BAT
AUX
VEHICLE
BATTERY BOX
3. Fasten 150 amp circuit breaker to bat-
tery box with two 1/4”-20 bolts and nuts,
and 1/4” washers supplied with parts kit.

13
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
STEP 3 - CONNECT POWER CABLE
INSTALLING LUG ON POWER CABLE
FIG. 13-2
POWER
CABLE
FIG. 13-2A
COPPER
TERMINAL
LUG
HEAT SHRINK
TUBING
FIG. 13-2B
1. Unbolt cover, disconnect taillight
wiring harness, and remove cover
from main housing (FIG. 13-1).
2. Run power (+) cable through grommet on bottom of main hous-
ing (FIG. 13-2). On the bare wire end of red power (+) cable, keep
enough length to attach copper terminal lug (Kit item) and reach
motor starter switch without putting tension on cable (after con-
nection) (FIGS. 13-1 and 13-2). Measure (if needed), and then cut
excess cable from bare wire end of cable. Put heat shrink tubing
(Kit item) (FIG. 13-2A) on the end of the cable and leave room for
terminal lug. Crimp and solder copper terminal lug on the power
(+) cable and shrink the heat shrink tubing over the barrel-end of
the lug (FIG. 13-2B).
COVER REMOVED FROM MAIN HOUSING
FIG. 13-1
BOLT, FLAT WASHER
& LOCK WASHER
(4 PLACES)
GROMMET

14
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
3. Remove hex nut from battery power ter-
minal on the starter switch (FIG. 14-1).
Connect power cable to starter switch
as shown in FIG. 14-1. Reinstall and
tighten hex nut.
Do not over-tighten the terminal nuts on starter solenoid. For the load ter-
minals, torque nuts to 30-35 lb-in max. Torque the nuts on #10-32 control
terminals 10-15 lb-in.
CAUTION
NOTE: Do not remove fl at washer from battery power terminal on starter switch.
STEP 3 - CONNECT POWER CABLE - Continued
CONNECTING POWER CABLE TO STARTER SWITCH
FIG. 14-1
POWER
CABLE
STARTER
SWITCH
BATTERY POWER
TERMINAL
HEX NUT

15
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
STEP 4 - CONNECT GROUND CABLE
NOTE: To ensure power unit is grounded correctly, connect black ground (-) cable
(Kit item) to grounding point on pump manifold and common ground point
on vehicle.
GROUND
CABLE
PUMP
MANIFOLD
GROMMET
FIG. 15-1B
COPPER
TERMINAL
LUG
HEAT SHRINK
TUBING
FIG. 15-1C
1. Run ground (-) cable through grommet on bottom of
main housing (FIGS. 15-1 and 15-1A). On the bare
wire end of ground (-) cable, keep enough length
to attach copper terminal lug (Kit item) and reach
grounding point on pump manifold without putting
tension on cable (after connection) (FIG. 15-1A).
Measure (if needed), and then cut excess cable
from bare wire end of cable (FIG. 15-1B). Put heat
shrink tubing (Kit item) on the end of the cable and
leave room for terminal lug. Crimp and solder cop-
per terminal lug on the ground (-) cable and shrink
the heat shrink tubing over the barrel-end of the lug
(FIG. 15-1C).
INSTALLING LUG ON GROUND CABLE
FIG. 15-1
FIG. 15-1A

16
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
STEP 4 - CONNECT GROUND CABLE - Continued
2. Remove hex bolt from grounding point
on pump manifold (FIG. 16-1). Then,
bolt lug on the ground cable to ground-
ing point on manifold (FIG. 16-1).
Torque bolt to 18-22 lb-ft.
CONNECTING GROUND CABLE TO POWER UNIT
FIG. 16-1
GROUND
CABLE
PUMP
MANIFOLD GROMMET
GROUNDING
POINT
BOLT
TERMINAL
LUG

17
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
STEP 5 - CONNECT POWER & GROUND CABLES
TO VEHICLE BATTERIES
1. Connect power (+) cable with
150 amp circuit breaker for
Liftgate to (+) terminal on OEM
vehicle battery (FIG. 17-1).
CONNECTING POWER & GROUND
CABLES TO OEM VEHICLE BATTERY
FIG. 17-1
BATTERY BOX
GROUND
(-) CABLE
POWER
(+) CABLE
150 AMP
CIRCUIT BREAKER
Make sure vehicle battery cables are disconnected before connectiong lift-
gate power (+) and ground (-) cables to vehicle battery.
CAUTION
!
3. Reconnect OEM vehicle battery
cables to OEM vehicle battery.
2. Connect ground (-) cable for
Liftgate to (-) terminal on OEM
vehicle battery (FIG. 17-1).

18
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
STEP 5 - PRESSURIZE HYDRAULIC SYSTEM
CONNECTING HANDHELD CONTROL
FIG. 18-1
To prevent injury and equipment damage, pressurize hydraulic system before
removing lower support fi xtures and operating Liftgate.
WARNING
!
2. Remove handheld control from
holder (FIGS. 18-1 and 18-1B).
To pressurize hydraulic system,
press UP button for 5-10 seconds
(FIG. 18-2A). Then, release the
button (FIG. 18-1B).
1. Get handheld control from
parts kit. Next, open the elec-
trical connector cover on the
RH column of liftgate (FIGS.
18-1 and 18-1A). Place hand-
held control in holder and plug
control cable in electrical con-
nector (FIG. 18-1A).
HANDHELD CONTROL
CONNECTED
FIG. 18-1A
CONNECTOR
& COVER
HANDHELD
CONTROL &
HOLDER
CONTROL SWITCH
(UP)
FIG. 18-2A
USING CONTROL TO PRESSURIZE
HYDRAULIC SYSTEM
FIG. 18-2

19
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
STEP 6 - CHECKING HYDRAULIC FLUID
3. If needed, add fl uid to the reser-
voir as follows. Remove fi ller cap
(FIG. 19-2). Fill the reservoir with
hydraulic fl uid to level shown in
FIG. 19-2. Reinstall fi ller cap.
POWER UNIT FLUID LEVEL
(FIG. 19-2
2. Check the hydraulic fl uid level in
reservoir as follows. With platform
on the ground, level should be as
shown in FIG. 19-2.
CAUTION
Keep dirt, water and other contaminants from entering the hydraulic system.
Before opening the hydraulic fl uid reservoir fi ller cap, drain plug and hydraulic
lines, clean up contaminants that can get in the openings. Also, protect the
openings from accidental contamination.
Never mix synthetic fl uids with conventional hydraulic fl uids. Hydraulic system
must be purged if the fl uids are mixed.
NOTE: Liftgate is shipped with Exxon Univis HVI-13 hydraulic fl uid in the hydraulic
cylinders. Exxon Univis HVI-13 hydraulic fl uid is recommended for operating
temperatures of -40 to +120° F. Refer to decal in pump box. Under certain
conditions, other brands and grades of oil may be used as substitutes for the
recommended oil. See TABLES 20-1 for recommended brands of ISO 15 oil.
1. Unfold and lower platform to
the ground (FIG. 19-1). Refer to
Operation Manual for detailed
operating instructions.
3-3/4” MAX
POWER UNIT
(REF)
FILLER CAP
RESERVOIR
3-1/4” MIN
PLATFORM OPEN ON THE GROUND
GROUND FIG. 19-1

20
11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]
STEP 6 - CHECKING HYDRAULIC FLUID - Continued
TABLE 20-1
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
ROSEMEAD THS FLUID 17111