Kubota WSM LA271 Instruction manual

WORKSHOP MANUAL
. FRONT LOADER
LA271·LA301·LA351·LA401
LA272·LA302·LA352·LA402
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TO THE READER
This Workshop Manual has been prepared to provide servIcing personnel with
information
on the mechanism, service and maintenance of KUBOTA Front Loaders. It is
divided into two parts, "Mechanism" and "Servicing".
•Mechanism
Information on the construction and function are included. This part should be
understood before proceeding with troubleshooting, disassembling and servicing.
•Servicing
Under the heading "General" section comes general precautions, check and
maintenance and special tools. Other section, there are troubleshooting, servicing
specification lists, checking and adjusting, disassembling and assembling, and servicing
which cover procedures, precautions, factory specifications and allowable limits.
All information, illustrations and specifications contained
in this manual are based on
the latest production information available at the time of publication.
The right
is reserved to make changes in all information at any time without notice.
January 2000
©KUBOTA Corporation 2000 17021200010
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SAFETY INSTRUCTIONS
LA271 • LA301 • LA351 • LA401 •LA272 • LA302· LA 352· LM02 WSM, 17021
~//HH/H//H/H//H////H///HH//H///~/H////HH//HHH/HH///////////////////H//~///////HH~H////H/H//////H///~
~ ASAFETY FIRST ~
~ This symbol, the industry's "Safety Alert Symbol", is used throughout this manual and decals on ~
~ the machine itself to warn of the possibility of personal injury. Read these instructions carefully. ~
~ It is essential that you read the instructions and safety regulations before you attempt to repair or ~
~ use this unit. ~
~/.M'.M'///H'HHH////7H.6¥/.///7.6¥/.///7H//7/.H///////HH//7/~/H~H/~H////~H///H'/////H'//7/.6¥/.///7////7//////H~
ADANGER :Indicates an imminently hazardous situation which, if not avoided, will result in death
or serious injury.
AWARNING:lndicates apotentially hazardous situation which, if not avoided, could result in death
or serious injury.
ACAUTION :Indicates a potentially hazardous situation which, if not avoided, may result in minor
or moderate injury.
•IMPORTANT :Indicates that equipment or property damage could result if instructions are not
followed.
I•NOTE :Gives helpful information. I
..... _---------
OOOOOZ00010
BEFORE SERVICING AND REPAIRING
(1) Read all instructions and safety instructions in this
manual and
on your machine safety decals.
(2) Clean the work area and machine.
(3) Park the machine on a firm and level ground, and set
the parking brake.
(4) Lower the implement to the ground.
(5) Stop the engine, and remove the key.
(6) Disconnect the battery negative cable.
(7) Hang a"DO NOT OPERATE" tag in operator
station.
00000F00010
OOOOOZ00020
1
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LA271 •LA301 • LA 351 •LA401 • LA272· LA302· LA 352· LA402 WSM, 17021 SAFETY INSTRUCTIONS
SAFETY STARTING
(1) Do not start the engine by shorting across starter
terminals or bypassing the safety start switch.
(2) Do not alter or remove any part of machine safety
system.
(3) Before starting the engine, make sure that all shift
levers are
in neutral positions or in disengaged
positions.
(4) Never start the engine while standing on ground.
Start the engine only from operator's seat.
00000F00020
OOOOOZ00030
00000F00030
C~
,
SAFETY WORKING
(1) Do not work on the machine while under the
influence
of alcohol, medication, or other substances
or while fatigued.
(2) Wear close fitting clothing and safety equipment
appropriate to the job.
(3) Use tools appropriate to the work. Makeshift tools,
parts, and procedures are not recommended.
(4) When servicing is performed together by two or more
persons, take care to perform all work safely.
(5) Do not work under the machine that is supported
solely by ajack. Always support the machine by
safety stands.
(6) Do not touch the rotating or hot parts while the engine
is running.
(7) Never remove the radiator cap while the engine is
running, or immediately after stopping. Otherwise,
hot water will spout out from radiator. Only remove
radiator cap when cool enough to touch with bare
hands. Slowly loosen the cap to first stop to relieve
pressure before removing completely.
(8) Escaping fluid (fuel or hydraulic oil) under pressure
can penetrate the skin causing serious injury.
Relieve pressure before disconnecting hydraulic or
fuel lines. Tighten all connections before applying
pressure.
OOOOOZ00040
00000F00050
+
•
-
2
AVOID FIRES
(1) Fuel is extremely flammable and explosive under
certain conditions. Do not smoke or allow flames or
sparks in your working area.
(2) To avoid sparks from an accidental short circuit,
always disconnect the battery negative cable first
and connect it last.
(3) Battery gas can explode. Keep sparks and open
flame away from the top
of battery, especially when
charging the battery.
(4) Make sure that no fuel has been spilled on the
engine.
OOOOOZ00050
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SAFETY INSTRUCTIONS
00000F00060
LA271 •
LA301 •LA351 •LA401 • LA272· LA302· LA 352· LA402 WSM, 17021
VENTILATE WORK AREA
(1) If the engine must be runn ing to do some work, make
sure the area
is well ventilated. Never run the engine
in aclosed area. The exhaust gas contains
poisonous carbon monoxide.
OOOOOZ00060
PREVENT ACID BURNS
(1) Sulfuric acid in battery electrolyte is poisonous. It is
strong enough to burn skin, clothing and cause
blindness
if splashed into eyes. Keep electrolyte
away from eyes, hands and clothing.
If you spill
electrolyte
on yourself, flush with water, and get
medical attention immediately.
OOOOOZ00070
DISPOSE OF FLUIDS PROPERLY
(1) Do not pour fluids into the ground, down adrain, or
into astream, pond,
or lake. Observe relevant
environmental protection regulations when disposing
of oil, fuel, coolant, electrolyte and other harmful
waste.
OOOOOZOOOBO
(
00000F00090
PREPARE FOR EMERGENCIES
(1) Keep afirst aid kit and fire extinguisher handy at all
times.
(2) Keep emergency numbers for doctors, ambulance
service, hospital and fire department near your
telephone.
OOOOOZ00090
3
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LA271 •LA301 •LA 351 • LA401 • LA272· LA302· LA 352· LA402 WSM, 17021
SAFETY INSTRUCTIONS
I S_A_F_E_T_Y_D_E_C_A_LS I
•The following safety decals are installed on the machine.
If adecal becomes damaged, illegible or
is not on the machine, replace it. The decal part number is
listed in the parts list.
LA401 .LA272 .LA302 .LA352 .LA402
v'
LA401 .LA272 .LA302 .LA352 .LA402
o
TO AVOIO SERIOUS INJURY
OR DEATH CAUSED BY
ROLLOVERS :
I. RCfS and a fastened stat btlt
are SHongl') recOMeroded tn
alll:lst ill appliutions. foldable
R<fS should b' in upr ighl .nd
lockedpoSlliOtlllflJJipPtd.
2. Adjust rear whtels to the widest
setting tN.1 is sUllable for
Ill< uDlI.
1. Add r eCOo'M\ended whee I
ballast or rtar uught for
slabilil~.
4. 00 l()J dr ive on sleep slepes
or unstabl e sud aces.
S. Carry loader aflls at low
position ~ing lransPQt'l.
Hovt' and urn tractor al slOll
speeds.
(3)Part No. 75546-56415
ADANGER
TO AVOID PERSONAL
INJURY :
I. Obstfve sa( et IJ pr ecaul ions
In loader and tractor
Operator's Manual.
2. Operate the loader (rQlll
tractor seat onl!;l.
3. Keep children. others and
Iivestock awa~ when operat-
Ing loader and traclGt.
4. Il'o'oid holes. loose ground.
and rodes which Illy cause
trlCH" I lOader \0 tlP·
S. \lhen parking or storing.
choosc f1.1 and hard 9'oood.
lower the bucket to the
ground. set brakes and
rel'lO'o'e key before leaving
tractor.
6. Be(cw(' disconnecting hyO-au·
lie IiNS. ,elieveilll hoJ*aulic
pressur ('.
(2)Part No. 75546-56451
ACAUTION
(5)part No. 75567-56422
TO AVOID SERIlXJS lNJlJlY
OR DEATH CAUSED BY
FALLl NG LOADS :
I. Load on ra I sed bucker or r .. 1
can fall Of roll back onlo
operator causing set ious
in;urlJ or dealh.
2. Use approved c1allping and
lor guard atlachotents ror
handl i"9 I at gr. I Dose or
shHtabl, loads such as bal",
pOSIS, sht<ls 01 pl\,<ood ,Ic.
1. c.rr~ h.ds as I .. as pOsslbl"
AWARNING
~~~I~
TO AVOID INJURY
FROM FALLS OR
BEING CRUSHED :
I. 00 my sla~d or work under
raised loader or bucket.
2. DO NOT use loader as a
work platter •.
1. HEVER connect chain. cable
.. roP' to load« bucl,t whJl&
operating loader.
(1)Part No. 75546-56441
(4)Part No. 75546-56431
ADANGER
~
(f"
CARE OF DANGER, WARNING AND CAUTION LABELS
1. Keep danger, warning and caution labels clean and free from obstructing material.
2. Clean danger, warning and caution labels with soap and water, dry with asoft cloth.
3. Replace damaged or missing danger, warning and caution labels with new labels from your local KUBOTA
Dealer.
4. .If acomponent with danger, warning and caution label (s) affixed is replace with new part, make sure new
label
(s) is (are) attached in the same locations (s) as the replaced component.
5. Mount new danger, warning and caution labels by applying on aclean dry suriace and pressing any bubbles to
outside edge.
17021F00010
17021Z00020
4
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TERMINOLOGY
TERMINOLOGY
17021F00020
LA271 •LA301 •LA351 •LA401 • LA272· LA302· LA352· LA402 WSM, 17021
1I-_---~7
(1) Bucket Cylinder
(2) Boom
(3) Hydraulic Control Valve
(4) Side Frame
(5) Mounting Pin
5
(6) Main Frame
(7) Bucket (8) Boom Cylinder (9) Brace
17021Z00030
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LA271 •LA301 • LA351 • LA401 • LA272' LA302' LA352' LA402 W8M, 17021
SPECIFICATIONS
LOADER SPECIFICATIONS
SPECIFICATIONS
Model LA271 LA301 LA351 LA401
ASAE Rated Lift Capacity 270
kg (595 Ibs) 300 kg (660 Ibs) 350
kg (770 Ibs) 400 kg (882 Ibs)
ASAE Rated Brakeout 4450 N(1000 Ibs) 5120 N(1150 Ibs) 5940 N(1335 Ibs) 7060 N(1586 Ibs)
Force
Boom Bore
38.1 mm (1.50 in.) 44.5
mm (1.75 in.)
Cylinder Stroke 307
mm (12.10 in.) 289 mm (11.40 in.) 435 mm (17.13 in.)
Bucket Bore
38.1 mm (1.50 in.) 44.5 mm (1.75 in.)
Cylinder Stroke 330 mm (13.00 in.) 450 mm (17.72 in.)
3Position One Detent Float
Bucket Control -Position, Power
Control Valve Type Beyond Circuit
Valve 4Position
Bucket Control One Detent Float Position, Two Stage Bucket Dump, Power Beyond Circuit
Valve Type
Relief Valve Setting 133.5 to 147.5 to 133.5 to 140.5 kgf/cm2
140 kgflcm2154.6 kgflcm2
Pressure (1900 to 2000 psi) (2100 to 2200 psi) (1900 to 2000 psi)
Net Weight (Approx.) 208
kg (460 Ibs) 216 kg (475 Ibs) 226 kg (500 Ibs) 280
kg (617 Ibs)
Model LA272 LA302 LA352 LA402
ASAE Rated Lift Capacity 270
kg (595 Ibs) 300 kg (660 Ibs) 350 kg (770 Ibs) 400
kg (882 Ibs)
ASAE Rated Brakeout 4460 N(1005Ibs) 4990 N(1120 Ibs) 5940 N(1335 Ibs) 7500 N(1685 Ibs)
Force
Boom Bore
38.1 mm (1.50 in.) 44.5 mm (1.75 in.)
Cylinder Stroke 307
mm (12.10 in.) 289 mm (11.40 in.) 435 mm (17.13 in.)
Bucket Bore
38.1 mm (1.50 in.) 44.5 mm (1.75 in.)
Cylinder Stroke 330 mm (13.00 in.) 450 mm (17.72 in.)
3Position
Bucket Control One Detent Float Position, Power Beyond Circuit
Control Valve Type
Valve 4Position
Bucket Control One Detent Float Position, Two Stage Bucket Dump, Power Beyond Circuit
Valve Type
Relief Valve Setting 133.5 to 147.5 to 133.5 to 140.5 kgf/cm2
140 kgf/cm2154.6 kgf/cm2
Pressure (1900 to 2000 psi) (2100 to 2200 psi) (1900 to 2000 psi)
Net Weight (Approx.) 208
kg (460 Ibs) 216 kg (475 Ibs) 226
kg (500 Ibs) 280
kg (617 Ibs)
17021Z00040
6
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SPECIFICATIONS
BUCKET SPECIFICATIONS
LA271 • LA301 •LA351 •LA401 • LA272· LA302· LA352· LA402 WSM, 17021
Model LA271, LA301
LA351 LA401
Type Square 48 Square 50 Square 54 Square 60LM
Width 1220 mm (48.0 in.) 1270
mm (50.0 in.) 1372 mm (54.0 in.) 1524 mm (60.0 in.)
Length 465 mm (18.3 in.) 490
mm (19.3 in.) 478 mm (18.8 in.) 518 mm (20.4 in.)
Height 490 mm (19.2 in.) 516 mm (20.3 in.) 530 mm (20.9 in.)
Struck 0.15 m3(5.2 cu.ft.) 0.16 m3(5.5 cu.ft.) 0.19 m3(6.7 cu.ft.) 0.23 m3
(8.1 cu.ft)
Capacity Heaped 0.17 m3(6.2 cu.ft.) 0.18 m3(6.5 cu.ft.) 0.23 m3
(8.1 cu.ft.) 0.28 m3(9.9 cu.ft)
Weight 54
kg (120 Ibs) 62
kg (137 Ibs) 79 kg (174 Ibs) 82
kg (181 Ibs)
Model LA272,LA302 LA352 LA402
Type Square 48 Square 50 Square 54 Square 60LM
Width 1220 mm (48.0 in.) 1270 mm (50.0 in.) 1372
mm (54.0 in.) 1524 mm (60.0 in.)
Length 500 mm (19.7 in.) 525 mm (20.7 in.) 530 mm (20.9 in.) 570 mm (22.4 in.)
Height 480 mm (18.9 in.) 485 mm
(19.1 in.) 525 mm (20.7 in.) 540 mm (21.3 in.)
Struck 0.15 m3(5.2 cu.ft.) 0.16 m3(5.5 cu.ft.) 0.19 m3(6.7 cu.ft.) 0.23 m3
(8.1 cu.ft)
Capacity Heaped 0.17 m3(6.2 cu.ft.) 0.18 m3(6.5 cu.ft.) 0.23 m3
(8.1 cu.ft.) 0.28 m3(9.9 cu.ft)
Weight 54
kg (120 Ibs) 62
kg (137 Ibs) 79 kg (174Ibs) 82
kg (181 Ibs)
17021Z00050
7
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LA271 •LA301 • LA351 • LA401 • LA272· LA302· LA352· LA402 WSM, 17021
OPERATING DIMENSIONS
DIMENSIONS
~
LA271 LA301 LA351 LA401 LA272 LA302 LA352 LA402
81700 82710
87300 82100 82400HST 82710 87400 87500 82410
Item 82400GEAR B2910
Maximum Lifting Height 1780
mm
1790 mm (70.5 in.) 2130
mm 1770 mm 1765 mm
1770mm 2090 mm
(A)
(70.1 in.) (83.9 in.) (69.7 in.) (69.5 in.) (69.7 in.) (82.3 in.)
Clearance with Bucket 1310
mm
1320 mm 1310 mm 1664 mm
1310 mm 1320
mm
1310 mm 1665 mm
Dumped (8) (51.6 in.) (52.0 in.) (51.6 in.) (65.5 in.) (51.6 in.) (52.0 in.) (51.6 in.) (65.6 in.)
Reach at Maximum 680mm
645mm 635 mm 660 mm
680 mm 645 mm
635 mm 660mm
Height (C) (26.8 in.) (25.4 in.) (25.0 in.) (26.0 in.) (26.8 in.) (25.4 in.) (25.0 in.) (26.0 in.)
Maximum Dump Angle 45 deg. 40 deg. 45 deg. 40 deg.
(D)
Reach with 8ucket on 1280
mm
1295 mm 1320 mm 1376
mm
1280 mm 1295 mm
1320 mm
1375 mm
Ground
(E)
(50.4 in.) (51.0 in.) (52.0 in.) (54.2 in.) (50.4 in.) (51.0 in.) (52.0 in.)
(54.1 in.)
8ucket Roll-back Angle 24 deg. 26 deg. 24 deg. 26 deg.
(F)
(G)
110mm
95 mm (3.7 in.) 185
mm
80 mm (3.15 in.)
135mm
Digging Depth (4.3 in.) (7.3 in.) (5.3 in.)
Overall Height inCarring 1150
mm
1160 mm (45.7 in.) 1195
mm
1150 mm 1160
mm (45.7 in.) 1195
mm
Position
(H)
(45.3 in.) (47.0 in.) (45.3 in.) (47.0 in.)
87300 (4WD) with 6 - 12 Front
llres and 8.3 -16 Rear llres.
81700 (4WD) with 6 -12 Front llres and 8.3 -16 Rear llres.
82100 (4WD) with 6 - 12 Front llres and 9.5 -16 Rear llres.
82400 (4WD) with 7 - 12 Front lires and 11.2 -16 Rear lires.
82710 (4WD) with 7 - 12 Front lires and 12.4 -16 Rear lires.
B7400 (4WD) With 6 - 12 Front lires and 8.3 - 16 Rear lires.
B7500 (4WD) with 6 -12 Front lires and 9.5 -16 Rear lires.
82410 (4WD) with 7- 12 Front lires and 11.2 -16 Rear lires.
82710 (4WD) with 7 - 12 Front lires and 12.4 -16 Rear lires.
82910 (4WD) with 7 - 12 Front lires and 12.4 -16 Rear lires.
AB H
12210F00030 17021200060
PERFORMANCE RATINGS (NO LOAD)
~
LA271 LA301 LA351 LA401 LA272 LA302 LA352 LA402
Item
Raise to Full Height 3.9 sec. 2.9 sec. 3.3 sec. 3.2 sec. 3.3 sec. 2.7 sec:
3.1 sec. 3.2 sec.
Lowering Time 3.0 sec. 2.3 sec. 2.6 sec. 2.4 sec. 2.5 sec. 2.2 sec. 2.5 sec. 2.4 sec.
Attachment Roll-back 2.5 sec. 2.0 sec. 2.7 sec. 2.4 sec. 2.2 sec. 1.8 sec. 2.5 sec. 2.4 sec.
Time
Attachment Dump Time
2.1 sec. 1.6 sec. 2.0 sec. 1.9 sec. 1.9 sec. 1.6 sec. 1.9 sec. 1.9 sec.
17021200070
8
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MECHANISM
CONTENTS
[1] FEATURES M-1
[2] HYDRAULIC CIRCUIT M-2
[3] CONTROL VALVE ASSEMBLy M-3
(1) LA271 •
LA301 • LA351 (Old Type Valve) M-3
(2) LA271 •
LA301 • LA351 (New Type Valve) and
LA401 •LA272 •LA302 •LA352 •LA402
(4 Position Bucket Control) M-11
(3) LA401· LA272· LA302 • LA352· LA402
(3 Position Bucket Control) M-19
[4] RELIEF VALVE M-23
[5] BOOM CYLINDER AND BUCKET CYLINDER M-25
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LA271 • LA301 •LA351 •LA401 • LA272· LA302· LA352· LA402 WSM, 17021
[1] FEATURES
17021 F00030
(1) Huge Hoisting and Scooping Power
(2) Fast Cycle Time
(3) One-Lever Operation
(4) Heavy-Duty Bucket
(5) Long Arm Reach
(6) Series Circuit Hydraulic Control Valve
M-1
MECHANISM
17021M00010
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MECHANISM
LA271 • LA301 • LA351 •LM01 •LA272· LA302· LA352· LM02 WSM, 17021
[2] HYDRAULIC CIRCUIT
•4Position Bucket Control
'------ To Transmission Case
--- .. ..q--- +-~=- ---
P T
From Hydraulic Pump
LA271 /LA301 /LA351 /LA401 /LA272 /LA302 /LA352 /LA402
2
To 3-point Hydraulic System
17020F00040
•3Position Bucket Control
'------+- To Transmission Case
'7
/.:J <9 ( ;'//1
4
(]L'C kef
3
I
L_ -Q------\~ _
LA401 /LA272 /LA302 /LA352 /LA402
From Hydraulic Pump
To 3-point Hydraulic System
17020F00050
(1) Boom Control Valve
(2) Bucket Control Valve
(3) Bucket Cylinder
(4) Boom Cylinder (5) Control Vavle Assembly
(6) Relief Valve
(7) Hydraulic Block
17021M00020
M-2
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LA271 • LA301 • LA351 • LA401 • LA272· LA302· LA352· LA402 WSM, 17021
[3] CONTROL VALVE ASSEMBLY
(1) LA271 •LA301 •LA351 (Old Type Valve)
2
MECHANISM
®
2
3
17020F00060
T
A1 ~1'---------'
81 ~'I'- -J
A2~------------'
82~' ----------'
P
T
4
P
'----+--~ P8
P: PPort
T: TPort
(3) Bucket Control Section
The bucket control valve is of 4-position, 6-
connection, no detent, spring center type, consisting
of amono block valve housing, spool, load check
valve, etc. This valve has A2 and B2 ports and
controls oil flow
to the bucket cylinder.
(4) Power Beyond
This section has PB port which is connected to the
power beyond port of hydraulic block by the hydraulic
hose, and feeds oil to the three point hydraulic control
valve.
(1) Inlet and Outlet Section
(2) Boom Control Valve
(3) Bucket Control Valve
(4) Power Beyond
(5) Relief Valve
The control valve assembly is composed of one
casting block and four major section
as shown above.
And the relief valve is installed on this valve.
(1) Inlet and Outlet Section
This section has Pand Tports.
The Pport
is connected to the pump port of hydraulic
block by the hydraulic hose.
The Tport
is connected to the return port of
transmission case by the hydraulic hose.
(2) Boom Control Section
The boom control valve is of 4-position, 6-connection,
detent, spring center type, consisting
of amono block
valve housing, spool, load check valve, etc. This
valve has A1 and B1 ports and controls oil flow to the
boom cylinder.
A1: A1 Port
A2: A2 Port
81: 81 Port
82: 82 Port
P8: P8 Port
17020M00030
M-3
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MECHANISM
•Neutral
®
LA271 • LA301 • LA351 • LM01 • LA272' LA302 •LA352 • LM02 WSM, 17021
r"-'
I
A1
81 ~1'---------l
A2 ~-------'
82 }- ---l 1-------1
2
7
17020F00070
4
6
95
(6) PB Passage 1
(7) PB Passage 2
(8) Load Check Valve
(9) Load Check Valve
the spools (1), (2) to the PB port through the PB
passage 1 (6) and 2(7).
3. Then the oil is fed to the three point hydraulic system
from the
PB port.
(1) Spool
(2) Spool
(3) Relief Valve
(4) Boom Control Section
(5) Bucket Control Section
1. Pressure-fed oil from the hydraulic pump is delivered
into Pport.
2.
As the load check valve (8), (9) are kept closed in the
neutral position, oil flows along the notched section of
P: PPort (From Pump Port of
Hydraulic Block)
T: TPort (To Return Port of
Transmission Case)
A1 : A1 Port
A2: A2 Port
B1: B1 Port
B2: B2 Port
PB: PB Port (To Power Beyond
Port of Hydraulic Block)
17020M00040
M-4
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LA271 • LA301 • LA351 • LM01 •LA272 •LA302 • LA352· LM02 WSM, 17021
MECHANISM
1. When the hydraulic control lever is set to the "UP"
position, the spool
(1) of the boom control section (3)
moves to the left, which forms oil passages between
passage 1
(6) and B1 port, and between A1 port and
PB passage 1(2).
2. The pressure-fed oil from the Pport opens the load
check valve
(5) and flows through the notched
section of the spool
(1) and B1 port to extend the
boom cylinder.
3. Return oil from the boom cylinder flows from the A1
port through the passage
in the spool (1) and PB
passage 1 (2) to the bucket control section (4).
•
L---1>--------- L.C\--_----< PB
(1) Spool
(2)
PB Passage 1
(3) Boom Control Section
(4) Bucket Control Section
(5) Load Check Valve
(6) Passage 1
P: PPort
T: TPort
A1: A1 Port (From Boom
Cylinder)
B1: B1 Port (To Boom Cylinder)
PB: PB Port
®6
17020F00080
M-5
17020M00050
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MECHANISM LA271 • LA301 •LA351 • LA401 • LA272· LA302· LA352· LA402 WSM, 17021
•Down
'-_---.,>-- ---J '--'r-----4P8
®
1. When the hydraulic control lever is set to the
"DOWN" position, the spool (1) moves to the right,
which forms oil passages between passage 1
(6) and
A1 port, and between B1 port and PB passage 1(2).
2. The pressure-fed oil from the Pport opens the load
check valve
(5) and flows through the notched
section
of the spool (1) and A1 port to retract the
boom cylinder.
3. Return oil from the boom cylinder flows from the B1
port through the passage in the spool (1) and PB
passage 1 (2) to the bucket control section (4).
(1) Spool P: PPort
(2)
P8 Passage 1 T: TPort
(3) Boom Control Section
A1 : A1 Port (To Boom Cylinder)
(4) Bucket Control Section 81: 81 Port (From Boom
(5) Load Check Valve Cylinder)
(6) Passage 1
P8: P8 Port
17020F00090 17020M00060
M-6
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