Hyundai 20D-7 User manual

SERVICE MANUAL
HYUNDAI
FORKLIFT
20D-7
25D-7
30D-7
33D-7

CONTENTS
SECTION 1 GENERAL
Group 1 Safety Hints
---------------------------------------------------------------------------------------------------- 1-1
Group 2 Specifications
-------------------------------------------------------------------------------------------------
1-5
Group 3 Periodic Replacement
------------------------------------------------------------------------------------ 1-13
SECTION 2 REMOVAL AND INSTALLATION OF UNIT
Group 1 Structure --------------------------------------------------------------------------------------------------------- 2-1
Group 2 Removal and Installation of Unit -------------------------------------------------------------------- 2-2
SECTION 3 POWER TRAIN SYSTEM
<OLD Transmission and drive axle>
Group 1 Structure and Operation
--------------------------------------------------------------------------------- 3-1
Group 2 Troubleshooting ---------------------------------------------------------------------------------------------- 3-21
Group 3 Disassembly and Assembly --------------------------------------------------------------------------- 3-25
<NEW Transmission and drive axle>
Group 1 Structure and Operation
-------------------------------------------------------------------------------- 3-76
Group 2 Troubleshooting ---------------------------------------------------------------------------------------------- 3-94
Group 3 Disassembly and Assembly
--------------------------------------------------------------------------- 3-100
SECTION 4 BRAKE SYSTEM
Group 1 Structure and Function ----------------------------------------------------------------------------------- 4-1
Group 2 Operational Checks and Troubleshooting ------------------------------------------------------ 4-8
Group 3 Tests and Adjustments
----------------------------------------------------------------------------------- 4-10
SECTION 5 STEERING SYSTEM
Group 1 Structure and Function ----------------------------------------------------------------------------------- 5-1
Group 2 Operational Checks and Troubleshooting ------------------------------------------------------ 5-10
Group 3 Disassembly and Assembly --------------------------------------------------------------------------- 5-12
SECTION 6 HYDRAULIC SYSTEM
Group 1 Structure and Function ----------------------------------------------------------------------------------- 6-1
Group 2 Operational Checks and Troubleshooting ------------------------------------------------------ 6-18
Group 3 Disassembly and Assembly --------------------------------------------------------------------------- 6-22
SECTION 7 ELECTRICAL SYSTEM
Group 1 Component Location -------------------------------------------------------------------------------------- 7-1
Group 2 Electrical Circuit ---------------------------------------------------------------------------------------------- 7-2

Group 3 Component Specification ------------------------------------------------------------------------------- 7-10
Group 4 Connector Destination ----------------------------------------------------------------------------------- 7-11
Group 5 Troubleshooting
---------------------------------------------------------------------------------------------- 7-13
SECTION 8 MAST
Group 1 Structure --------------------------------------------------------------------------------------------------------- 8-1
Group 2 Operational Checks and Troubleshooting
------------------------------------------------------ 8-5
Group 3 Adjustment
----------------------------------------------------------------------------------------------------- 8-8
Group 4 Removal and Installation -------------------------------------------------------------------------------- 8-11

0-1
FOREWORD
1. STRUCTURE
This service manual has been prepared as an aid to improve the quality of repairs by giving the
serviceman an accurate understanding of the product and by showing him the correct way to perform
repairs and make judgements. Make sure you understand the contents of this manual and use it to
full effect at every opportunity.
This service manual mainly contains the necessary technical information for operations performed in
a service workshop.
For ease of understanding, the manual is divided into the following sections.
SECTION 1 GENERAL
This section gives the general information of the machine and explains the safety hints for
maintenance.
SECTION 2 REMOVAL & INSTALLATION OF UNIT
This section explains the procedures and techniques of removal and installation of each component.
SECTION 3 POWER TRAIN SYSTEM
This section explains the structure of the transmission as well as control valve and drive axle.
SECTION 4 BRAKE SYSTEM
This section explains the brake piping, each component and operation.
SECTION 5 STEERING SYSTEM
This section explains the structure of the steering unit, priority valve, trail axle as well as steering
circuit and operation.
SECTION 6 HYDRAULIC SYSTEM
This section explains the structure of the gear pump, main control valve as well as work equipment
circuit, each component and operation.
SECTION 7 ELECTRICAL SYSTEM
This section explains the electrical circuit and each component.
It serves not only to give an understanding electrical system, but also serves as reference material for
troubleshooting.
SECTION 8 MAST
This section explains the structure of mast, carriage, backrest and forks.
The specifications contained in this service manual are subject to change at any time and without any
advance notice. Contact your HYUNDAI distributor for the latest information.

0-2
Revised edition mark(
ΗΘΙÄ )
When a manual is revised, an edition mark is
recorded on the bottom outside corner of the
pages.
R
Revisions
Revised pages are shown at the list of revised
pages on the between the contents page and
section 1 page.
Symbols
So that the shop manual can be of ample
practical use, important places for safety and
quality are marked with the following symbols.
2. HOW TO READ THE SERVICE MANUAL
Distribution and updating
Any additions, amendments or other changes will
be sent to HYUNDAI distributors.
Get the most up-to-date information before you
start any work.
Filing method
See the page number on the bottom of the
page.
File the pages in correct order.
Following examples shows how to read the
page number.
Example 1
2 - 3
Item number(2. Structure and
Function)
Consecutive page number for
each item.
Additional pages : Additional pages are
indicated by a hyphen(-) and number after the
page number. File as in the example.
1.
2.
3.
Symbol Item Remarks
Special safety precautions are
necessary when performing the
work.
Extra special safety precautions
are necessary when performing
the work because it is under
internal pressure.
Special technical precautions or
other precautions for preserving
standards are necessary when
performing the work.
Safety
Caution
ö
10 - 4
10 - 4 - 1
10 - 4 - 2
10 - 5
Added pages

SECTION 2 REMOVAL AND INSTALLATION OF UNIT
Group 1 Structure --------------------------------------------------------------------------------------------------------- 2-1
Group 2 Removal and Installation of Unit -------------------------------------------------------------------- 2-2

2-1
GROUP 1 STRUCTURE
SECTION 2 REMOVAL & INSTALLATION OF UNIT
1
2
3
4
5
6 7 8 9 10 1112 1314
15
16
17
18
1920
21
1 Mast
2 Lift cylinder
3 Tilt cylinder
4 Main control valve
5Fork
6 Front wheel
7 Drive axle
8 Transmission
9 Torque converter
10 Engine
11 Steering cylinder
12 Hydraulic pump
13 Steering axle (Rear)
14 Rear wheel
15 Muffler
16 Counterweight
17 Radiator
18 Seat
19 Overhead guard
20 Steering wheel
21 Air cleaner
20D7OM21

Forks
Lower the fork carriage until the forks are
approximately 25
mm
(1 in ) from the floor.
Turn knob up and slide one fork at a time
toward the center of the carriage where a
notch has been cut in the bottom plate for
easy removal.
Remove only one fork at a time.
On larger forks it may be necessary to
use a block of wood.
2-2
GROUP 2 REMOVAL AND INSTALLATION OF UNIT
1. MAST
REMOVAL
1)
(1)
Remove and install following units as explained in the flow chart.
Backrest
Knob
Carriage
Center notch
Fork
Pin
Spring
Backrest (If necessary)
Remove bolts securing backrest to fork
carriage. Lift backrest straight up and
remove it from carriage.
(2)
Backrest
Bolt
Carriage
20D7RE02
20D7RE03
Η
Θ
Ι
ö
Η
CCarriage
With the mast vertical, raise the carriage
high enough to place blocks under the
load forks. This is done to create slack in
the load chains when the carriage is
lowered. Lower the carriage all the way
down to the floor. Make sure the carriage
is level, this will prevent any binding when
the mast is raised.
(3)
20D7RE04
Η

2-3
While supporting lift chains, remove nuts
and split pin from the anchor bolt.
Θ
Outer mast
Lift chain
Nut
Split pin
20D7RE05
Pull the chains out of the sheaves and
drape them over the front of the carriage.
Ι
Carriage
Lift chain
Mast
Block
20D7RE06
Slowly raise inner mast upright until mast
clears top of fork carriage. Move carriage
to work area and lower the mast.
Make sure that carriage remains on
floor and does not bind while mast is
being raised.
Inspect all parts for wear or damage.
Replace all worn or damaged parts.
Κ
ö
Inner mast
Carriage
Lift chain
20D7RE07

3-63
Fasten RING BRG ADJUST.
Κ
20D7AXLE065
20D7AXLE066
20D7AXLE067
Paint marking(Both sides)
20D7PT35
Measure backlash again.
Bachlash of pinion shaft and ring gear is 0.15~0.2
mm
(0.006~0.008 in)
If backlash is wrong, carry out adjusting work.
Adjust the left / right of RING BRG ADJUST by one
and one clip.
Λ
ö
ö
Fit position.
Μ
Assemble cotter pin.
Ν
60%
40~75%
40~75%
60%
40%
40%
Heel
Toe Toe
Heel
Drive side(Forward) Coast side (Reverse)
20D7PT37
After assembling, adjust pattern of the gear and
pinion shaft as figure.
If pattern is not adjusted, take a measure as
measuring backlash again and then reassemble.
ö

3-64
Pressurize lock pin into drive axle.
Η
20D7AXLE069
20D7AXLE070
20D7AXLE071
Spread sealant on the installation surface of carrier.
Θ
Fix assembly guide bar.
Ι
20D7AXLE072
Fit carrier at drive axle housing.
Spread loctite #5127 on drive axle housing.
Κ
ö
Spread loctite #277 on the spring washer bolt.
Λ
20D7AXLE073
AAssembly of carrier assembly

3-65
20D7AXLE074
Temporarily assemble bolt and confirm torque.
 Tightening torque : 6~7 kgfÂm
(43~51 lbfÂft )
Μ
Fix large quad ring into brake.
Η
20D7AXLE075
20D7AXLE076
20D7AXLE077
Fix small quad ring into brake.
When assembling quad ring, pay attent to chopping.
Θ
ö
Spread oil on the piston.
Ι
20D7AXLE078
Fix piston into drive axle housing.
Κ
TTRAVELING BRAKE SYSTEM ASSEMBLY
Piston assembly
(2)

5-3
4
TLS
LR
P
5
G
T/M
1
811
MCV
2
10MPa
P
T
LS CF EF
D
20D7SS03
NEUTRAL
1)
The steering wheel is not being operated so control spool(G) does not move.
The oil from hydraulic gear pump(1) enters port P of priority valve(2) and the inlet pressure oil
moves the spool(D) to the left.
Oil flow into LS port to the hydraulic tank(11).
So, the pump flow is routed to the main control valve.

5-4
4
TLS
LR
P
5
G
H
T/M
1
811
MCV
2
10MPa
P
T
LS CF EF
D
20D7SS04
LEFT TURN
2)
When the steering wheel is turned to the left, the spool(G) within the steering unit(4) connected with
steering column turns in left hand direction.
At this time, the oil discharged from the pump flows into the spool(G) within the steering unit(4)
through the spool(D) of priority valve(2) and flows to the gerotor(H).
Oil flow from the gerotor(H) flows back into the spool(G) where it is directed out of the left work
port(L).
Oil returned from cylinder returns to hydraulic tank(11).
When the above operation is completed, the machine turns to the left.

29
30
17
28
16 15
12 13
14
8910
11
SECTION E - E
31
18
SECTION T - T
6
2
EGF
G
FI57
E
FF
I
3
4
1
21
20 VIEW I - I
22
23
19
32
VIEW G - G
H
H
24
T
15
T
22
23
15
19
89
VIEW F - F
SECTION H - H
26
25
27
6-8
3. MAIN CONTROL VALVE
STRUCTURE (4- Spool)
20D7HS07
1 Lift block assy
2 Tilt block assy
3 Aux1 block assy
4 Aux2 block assy
5 T cover
6 Gauge plug assy
7 Long bolt
8 Hydrostat plug
9 O-ring
10 Hydrostat spring
11 Hydrostat sleeve
12 Relief piston
13 Nut
14 Relief plug
15 O-ring
16 Relief spring
17 Pilot poppet
18 Plug
19 O-ring
20 O-ring
21 O-ring
22 O-ring
23 O-ring, retainer
24 Plug
25 Steel ball
26 Load sensor spring
27 Load sensor spring
28 O-ring
29 System relief seat
30 Secondary relief seat
32 Solenoid valve assy
1)
Port name
Inlet port
Outlet port
Size
1-1/16-12UNF-2B
1-1/16-12UNF-2B

6-9
INLET SECTION OPERATION
Structure and description
12 13
14
16
28
17
30
8
910
29
11
Relief valve piston
(Relief valve piston)
T
2)
(1)
20D7HS08
8 Hydrostat plug
9 O-ring
10 Hydrostat spring
11 Hydrostat sleeve
12 Relief piston
13 Nut
14 Relief plug
16 Relief spring
17 Pilot poppet
28 O-ring
29 System relief seat
30 Secondary relief seat