Maxon DMD-22, DMD-33 Maintenance Manual

M-16-40
AUGUST 2018

© MAXON Lift Corp. 2018

11921 Slauson Ave.
Santa Fe Springs, CA. 90670

LIFT CORP.

CUSTOMER SERVICE:

TELEPHONE [phone] TOLL FREE [phone]

FAX: [phone]

NOTE: For latest version of all Manuals (and replacements), download the

Manuals from Maxon’s website at www.maxonlift.com.

WARRANTY/ RMA POLICY & PROCEDURE

LIFTGATE WARRANTY

Type of Warranty: Full Parts and Labor

Term of Warranty: Standard Liftgates - 2 years from ship date or 6,000 cycles
Premium Liftgates - 2 years from ship date or 10,000 cycles

This warranty shall not apply unless the product is installed, operated and maintained in accordance with MAXON Lift’s specifi cations as set forth in
MAXON Lift’s Installation, Operation and Maintenance manuals. This warranty does not cover normal wear, maintenance or adjustments, damage or
malfunction caused by improper handling, installation, abuse, misuse, negligence, or carelessness of operation. In addition, this warranty does not
cover equipment that has had unauthorized modifi cations or alterations made to the product.

MAXON agrees to replace any components which are found to be defective during the fi rst 2 years of service, and will reimburse for labor based on
MAXON’s Liftgate Warranty Flat Rate Schedule. (Copy of the Flat Rate is available at www.maxonlift.com.)

All warranty repairs must be performed by an authorized MAXON warranty facility. For any repairs that may exceed $500, including parts and labor,
MAXON’s Technical Service Department must be notifi ed and an “Authorization Number” obtained.

All claims for warranty must be received within 30 Days of the repair date, and include the following information:

1. Liftgate Model Number and Serial Number

2. The End User must be referenced on the claim

3. Detailed Description of Problem

4. Corrective Action Taken, and Date of Repair

5. Parts used for Repair, Including MAXON Part Number(s)

6. MAXON R.M.A. # and/or Authorization # if applicable (see below)

7. Person contacted at MAXON if applicable

8. Claim must show detailed information i.e. Labor rate and hours of work performed

Warranty claims can also be placed online at www.maxonlift.com. Online claims will be given priority processing.

All claims for warranty will be denied if paperwork has not been received or claim submitted via Maxon website for processing by MAXON’s Warranty
Department within 30 days of repair date.

All components may be subject to return for inspection, prior to the claim being processed. MAXON products may not be returned without prior written
approval from MAXON’s Technical Service Department. Returns must be accompanied by a copy of the original invoice or reference with original
invoice number and are subject to a credit deduction to cover handling charges and any necessary reconditioning costs. Unauthorized returns will be

refused and will become the responsibility of the returnee.

Any goods being returned to MAXON Lift must be pre-approved for return, and have the R.M.A. number written on the outside of the package in plain
view, and returned freight prepaid. All returns are subject to a 15% handling charge if not accompanied by a detailed packing list. Returned parts
are subject to no credit and returned back to the customer. Defective parts requested for return must be returned within 30 days of the claim date for
consideration to:

10321 Greenleaf Ave., Santa Fe Springs, CA 90670

MAXON’s warranty policy does not include the reimbursement for travel time, towing, vehicle rental, service calls, oil, batteries or loss of income due to
downtime. Fabrication or use of non Maxon parts, which are available from MAXON, are also not covered.

MAXON’s Flat Rate Labor Schedule takes into consideration the time required for diagnosis of a problem.

All Liftgates returned are subject to inspection and a 15% restocking fee. Any returned Liftgates or components that have been installed or not returned
in new condition will be subject to an additional reworking charge, which will be based upon the labor and material cost required to return the Liftgate or
component to new condition.

PURCHASE PART WARRANTY

Term of Warranty: 1 Year from Date of Purchase.

Type of Warranty: Part replacement only. MAXON will guarantee all returned genuine MAXON replacement parts upon receipt and inspection of parts
and original invoice.
All warranty replacements parts will be sent out via ground freight. If a rush shipment is requested, all freight charges will be billed to the requesting
party.

MAXON Lift Corp.

Attn: RMA#__

TABLE OF CONTENTS

WARNINGS ........................................................................................................................... 6

SAFETY INSTRUCTIONS .................................................................................................... 7

LIFTGATE TERMINOLOGY .................................................................................................. 8

PERIODIC MAINTENANCE .................................................................................................. 9

PERIODIC MAINTENANCE CHECKS .................................................................................. 9

PREVENTATIVE MAINTENANCE (PM) CHECKLIST ......................................................... 10

CHECKING HYDRAULIC FLUID .........................................................................................11

CHANGING HYDRAULIC FLUID ........................................................................................ 13

PRESSURIZING HYDRAULIC SYSTEM ............................................................................ 15

TORSION BAR REPLACEMENT & ADJUSTMENT............................................................ 16

DECALS .............................................................................................................................. 26

SYSTEM DIAGRAMS ......................................................................................................... 28

PUMP MOTOR & VALVE OPERATION (MANUAL CLOSE) ............................................... 28

PUMP MOTOR & VALVE OPERATION (EQUIPPED WITH HYDRAULIC CLOSER) ......... 29

HYDRAULIC SCHEMATIC (MANUAL CLOSE) .................................................................. 30

HYDRAULIC SCHEMATIC (EQUIPPED WITH HYDRAULIC CLOSER) ............................ 31

ELECTRICAL SCHEMATIC (MANUAL CLOSE) ................................................................ 32

ELECTRICAL SCHEMATIC (EQUIPPED WITH HYDRAULIC CLOSER) ........................... 33

ELECTRICAL SCHEMATIC - JUMPER HARNESS ASSEMBLY ........................................ 34

ELECTRICAL SCHEMATIC - HOUSING COVER ASSEMBLY (WITHOUT LIGHTS) ......... 35

ELECTRICAL SCHEMATIC - HOUSING COVER ASSEMBLY (WITH FOUR LIGHTS) .... 36

ELECTRICAL SCHEMATIC - HOUSING COVER ASSEMBLY, FOREIGN VEHICLE

(WITH 6 LIGHTS ) ...............................................................................................................37

DMD ELECTRICAL VALUES .............................................................................................. 38

RECOMMENDED BOLT TORQUES .................................................................................. 39

THIS PAGE INTENTIONALLY LEFT BLANK

Comply with the following WARNINGS and SAFETY INSTRUCTIONS while maintaining
Liftgates. See Operation Manual for operating safety requirements.

!

WARNINGS

• 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.

• Correctly stow platform when not in use. Extended platforms could create a hazard for

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

people and vehicles passing by.

• Disconnect Liftgate power cable from battery before repairing or servicing Liftgate.

• 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 housing cover.

• 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.

WARNING

6

SAFETY INSTRUCTIONS

• 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.

• 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.

• Do not allow untrained persons to operate 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.

• 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.

SAFETY INSTRUCTIONS

• If an emergency situation arises (vehicle or Liftgate) while operating the Liftgate, release the con-

trol switch to stop 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, grat­ing 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 num­ber 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

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

7

LIFTGATE TERMINOLOGY

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

(BEHIND COVER)

COLUMN

POWER UNIT

RUNNER

UP/DOWN

CONTROL SWITCH

(INBOARD)

MAIN FRAME

TRANSIT

HOOK

PLATFORM

LATCH

UP/DOWN

CONTROL SWITCH

(OUTBOARD)

HOUSING

COVER

PLATFORM

FOLD/UNFOLD SWITCH

(IF EQUIPPED WITH

HYDRAULIC CLOSER)

8

PERIODIC MAINTENANCE

PERIODIC MAINTENANCE CHECKS

!

WARNING

Never operate the Liftgate with parts loose or missing.

NOTE: Photocopy the PM CHECKLIST on the next page to help keep track of periodic

maintenance on the Liftgate. Keep completed form with maintenance records.

Annually

Visually check the entire Liftgate for excessively worn parts and broken welds, especially
the hinge pins. See Parts Manual for replacement parts. Also, do the Semi-annual and

Quarterly Maintenance checks.

Semi-annually

Visually check the platform hinge pins for excessive wear and broken welds. See Parts
Manual for replacement parts. Also, do the Quarterly Maintenance checks.

Quarterly

Check the hydraulic fl uid level in the pump reservoir. Refer to the CHECKING HYDRAULIC
FLUID procedure in the PERIODIC MAINTENANCE section.

If hydraulic fl uid appears contaminated, refer to the CHANGING HYDRAULIC FLUID

procedure on following page.

Keep track of the grade of hydraulic fl uid in the pump reservoir. Never mix two different

grades of fl uid.

Check lines and fi ttings for chaffi ng and fl uid leaks. Replace if necessary.

Check electrical wiring for chaffi ng and make sure wiring connections are tight and free

of corrosion.

Check that all WARNING and instruction decals are in place and legible.

Check for loose or missing nuts, bolts, covers, roll pins, screws and pins.

Check that platform latch and transit hook mechanisms work correctly and no parts are

missing.

CAUTION

Damaged cylinder seals and contaminated hydraulic fl uid 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.

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

Check for rust and oily surfaces on Liftgate. If there is rust or oil on the Liftgate, clean it

off. Touch up the paint where bare metal is showing.

9

PM Interval: 3 Months Date: / /

Equipment: W/O # Location:

Mechanic: Serial # Model #

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

Check Appropriate Box. “

Satisfactory

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

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Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

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PERIODIC MAINTENANCE

PREVENTATIVE MAINTENANCE (PM) CHECKLIST

”

MAXON 1

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

st

, 2nd and 3rd Quarter Liftgate Preventative Maintenance (PM) Procedures

Verify if the Quarterly or Annual PM is due by checking the PM sticker on

1

the curbside Liftgate column.
2 Check for oil leaks at: cylinders, valves, and fi ttings.
3 Check for damage: platform, column, runners and hydraulic tubes.
4 Check for loose or missing nuts, bolts, covers, roll pins, screws and pins.

Check for cracked welds at: columns, runners, platform, main housing
5

and vehicle door frame.

Check platform lowering speed: Range is 16 - 30 seconds. Check
6

cylinder lock valves for proper operation.
7 Check platform pins and couplers.

8 Check platform raising speed: Range is 12-13 seconds.

Check that platform unlatches, unfolds & folds smoothly & latches
9

securely.

Check switches and wiring connections on Liftgate as well as pump

10

inside main housing. Also check ground straps.

Check the gear pump for unusual noise, i.e. squealing or extreme RPM

11

output.

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Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Checking Oil Level: gravity down with the platform unfolded and on the

ground. Oil level should be as shown in Installation Manual, “CHECKING

12

HYDRAULIC FLUID”. Check for contamination, change if needed.

13 Check batteries: load test, corrosion, cables, hold downs and water level.
14 Check all charging and ground cable connections.

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Corrected

Corrected

Corrected

Complete a new PM sticker and install it on the curbside column of the

Liftgate. The next PM date is 3 months from the completed PM date.

15

Indicate on the PM sticker if 1st, 2nd, 3rd or 4th PM.

Check that platform latch and transit hook mechanisms work correctly

16

and no parts are missing.

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Corrected

Corrected

th

Quarter Liftgate Preventative Maintenance (PM). Note: Includes steps 1-16

Corrected

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Corrected

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Satisfactory

Satisfactory

MAXON 4

Repair Required



Repair Required

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For more detailed information, please refer to the product maintenance manuals. Use only genuine Maxon replacement
parts for all repairs.

17 Change hydraulic fl uid.
18 Inspect wear on slide pads.

TABLE 10-1

10

PERIODIC MAINTENANCE

CHECKING HYDRAULIC FLUID

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. Refer to TABLES 12-1 & 12-2.

NOTE: If the hydraulic fl uid in the reservoir is contaminated, do the CHANGING
HYDRAULIC FLUID procedure in this section.

1. Open and lower platform to the
ground (FIG. 11-1). Refer to
Operation Manual for detailed
operating instructions.

2. Unbolt main housing cover
as shown in FIG. 11-1.
Remove cover.

BOLT,

LOCK WASHER &

FLAT WASHER

(3 PLACES)

3. Check the hydraulic fl uid level in
reservoir as follows. With platform
on the ground, level should be as
shown in FIG. 11-2.

4. If needed, add fl uid to the reservoir as

follows. Remove fi ller cap (FIG. 11-2).
Fill the reservoir with hydraulic fl uid to
level shown in FIG. 11-2. Reinstall fi ller
cap.

CAUTION

Main housing cover must be
correctly secured to prevent it
from becoming a hazard.

5. Bolt on the main housing cover

as shown in FIG. 11-1. Torque
the 5/16”-18 cover bolts from 10

to 14 lb-ft.

COVER

UNBOLTING/ BOLTING COVER
(PLATFORM ON THE GROUND)

FIG. 11-1

POWER UNIT

3-3/4” MAX

3-1/4” MIN

RESERVOIR

POWER UNIT FLUID LEVEL

FILLER CAP

(MANUAL CLOSE POWER UNIT SHOWN)

FIG. 11-2

11

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

(REF)

ISO 32 HYDRAULIC OIL

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

RECOMMENDED

BRANDS

CHEVRON HIPERSYN 32

KENDALL GOLDEN MV

SHELL TELLUS S2 VX 32

EXXONMOBIL UNIVIS N-32, DTE-24

PART NUMBER

TABLE 12-1

ISO 15 OR MIL-H-5606 HYDRAULIC OIL

RECOMMENDED

BRANDS

CHEVRON FLUID A, AW-MV-15

KENDALL GLACIAL BLU

SHELL TELLUS S2 VX 15

EXXONMOBIL UNIVIS HVI-13

ROSEMEAD THS FLUID 17111

PART NUMBER

TABLE 12-2

12