Caterpillar Cat 621G Wheel Scraper (Prefix CEP) Service Repair Manual (CEP00001 and up)

1
Service Repair Manual
Models 621G Wheel Tractor
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Product WHEEL SCRAPER Model 621G WHEEL SCRAPER
CEP Configuration 621G Wheel Scraper CEP00001-UP
(MACHINE)
Disassembly and Assembly 621G and 627G Wheel
Tractor-Scrapers Machine Systems Media Number
-RENR4248-01 Publication Date -01/08/2004
Date Updated -09/08/2004
i03538320
Piston Pump (Cushion-Hitch) - Assemble SMCS -
5070-016 5316-016 Assembly Procedure Table 1
Required Tools Required Tools Required Tools Required Tools
Tool Part Number Part Description Qty
A 1P-0510 Driver Group 1
B 1P-1854 Pliers 1
C 1P-1857 Pliers 1
D 8T-5096 Dial Indicator Gp 1
E 5N-5561 Silicone Lubricant 1
F 9S-3263 Thread Lock Compound 1
Note Cleanliness is an important factor. Before
assembly, all parts should be thoroughly cleaned
in cleaning fluid. Allow the parts to air dry.
Wiping cloths or rags should not be used to dry
parts. Lint may be deposited on the parts which
may cause later trouble. Inspect all parts. If
any parts are worn or damaged, use new
Caterpillar parts for replacement. Note Apply a
light film of 10W oil to all components before
assembly.
3
Illustration 1 g01071755 1. Use Tooling (C) in
order to install retaining ring (50) to pump
housing (27) .
Illustration 2 g01071756 2. Use Tooling (A) in
order to install lip seal (51) to the pump
housing. The sealing lip of the lip seal should
face toward the bearing cup. The lip seal must
seat against the retaining ring.
Illustration 3
g01071757
4

• Lower the temperature of bearing cup (52) . Use
  Tooling (A) in order to install bearing cup
• (52) to pump housing (27) . Install bearing cup
  (52) until the bearing cup seats.
• Use the following steps to determine the preload
  on the bearings of the pump assembly.

Illustration 4 g01071758 a. Lower the
temperature of shaft (37) . Use a suitable press
in order to install shaft (37) into bearing cone
(38) . Install shaft (37) until bearing cone (38)
is seated onto shaft (37) .
Illustration 5 g01071773 b. Install shaft (37)
into pump housing (27) .
5
Illustration 6 g01071774 c. Install shim (35)
and bearing cone (34) on pump shaft (37) .
Illustration 7 g01071775 d. Lower the
temperature of bearing cup (31) . Use Tooling (A)
and a suitable press in order to install bearing
cup (31) in pump head (22) . Install the bearing
cup until the cup is seated.
Illustration 8
g01071776
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• Illustration 9 g01071778
• Position pump head (22) onto pump housing (27) .
  Install bolts (21) but do not tighten bolts (21)
  at this point.
• Use a feeler gauge to measure the distance
  between the pump head and the pump housing. Take
  measurements at three equal locations on the
  surface between the pump head and the pump
  housing.
• The average of the three dimension should be zero
  to 0.050 mm (0.0020 inch).
• If the dimension is not correct remove shim (35)
  . Refer to Illustration 6. To achieve the
  correct dimension, grind the shim or replace shim
  (35) .
• When the correct dimension is achieved tighten
  bolts (21) and then invert the pump assembly.
• Use Tooling (D) , a suitable screwdriver, and a
  set of slip joint pliers to check the end play
  on shaft (37) . If end play exists on the shaft,
  repeat Step 4 until the correct dimension is
  reached.
• Remove bolts (21) and pump head (22) from pump
  housing (27) . Remove bearing cone (34) and shim
  (35) from shaft (37) . Remove shaft (37) .
• Proceed with the assembly of the piston pump.

8
Illustration 10 g01071456 5. Install brass
bearings (49) into pump housing (27) .
Illustration 11
g01071779
6. Install pins (44) into barrel (43) .
Illustration 12 g01071455 7. Install seat (48)
in order to secure pins (44) in barrel (43) .
9
Illustration 13 g01071454 8. Position barrel
(43) in a suitable press. Install spring (47) in
barrel (43) . Position retaining ring (46) on
top of the spring.
Illustration 14
g01071453
Improper assembly of parts that are spring loaded
can cause bodily injury. To prevent possible
injury, follow the established assembly procedure
and wear protective equipment.

• Position Tooling (A) and the suitable press on
  top of the spring and inside of retaining ring
• . Use Tooling (A) in order to depress the spring
  that is in barrel (43) . Use Tooling (B) in
  order to install retaining ring (46) that secures
  the spring in barrel (43) . Remove Tooling
• .

10
Illustration 15 g01071452 10. Install collar
bearing (45) to pins (44) and barrel (43) .
Illustration 16 g01071451 11. Install pistons
(42) to the original positions in retraction
plate (41) . Install pistons (42) and retraction
plate (41) to barrel (43) . Pistons (42) must be
installed to the original positions.
Illustration 17
g01071429
11
12. Position swashplate (39) to rotating group
(40) .

• Illustration 18 g01071427
• Install shaft (37) and bearing cone (38) to
  swashplate (39) and rotating group (40) .
• Apply clean hydraulic oil to the components of
  the pump.

Illustration 19 g01071426 15. Install pump
housing (27) to bearing cone (38) , swashplate
(39) , and rotating group (40) . Turn the pump
body over 180 degrees and hold the components in
the pump body.
12

• Illustration 20 g01071780
• Position pump housing (27) on suitable cribbing.
  Position shaft (37) between the two blocks of
  wood.
• Install bearing cone (34) and shim (35) to shaft
  (37) . Apply clean hydraulic oil to the bearing
  cone. Install O-ring seal (36) to pump housing
  (27) .
• Apply Tooling (E) onto plunger (25) .

Illustration 21 g01087607 19. Position plunger
(25) to the wear pad that is positioned on the
swashplate. Tooling (E) will hold plunger (25)
in place. Install spring (26) on plunger (25) .
13
Illustration 22 g01071783 20. Install the O-ring
seals to plugs (33) . Install plugs (33) to pump
head (22) . Tighten the plugs to a torque of 45
5 Nm (33 4 lb ft).
Illustration 23 g01071784 21. Install locating
pin (29) to pump head (22) . Apply Tooling (F)
onto the threads on piston guide (30) and
plunger guide (32) . Install the piston guide and
plunger guide into pump head (22) and tighten to
a torque of 80 Nm (60 lb ft). Apply Tooling (E)
onto guide (32) .
14
Illustration 24 g01071420 22. Apply Tooling (E)
onto the side of plate (23) that has Slot (X) .
Slot (X) will be positioned over locating pin
(29) when plate (23) is installed to the pump
head.
Illustration 25 g01071785 23. Install plate (23)
to pump head (22) . Install four O-ring seals
(28) to pump head (22) . Apply Tooling (E) onto
piston (24) . Install piston (24) to guide (32) .
Illustration 26
g01071786
Improper assembly of parts that are spring loaded
can cause bodily injury. To prevent possible
injury, follow the established assembly procedure
and wear protective equipment.
15

1. Install pump head (22) , plate (23) , piston (24)
   , plunger (25) , and spring (26) as a unit to
   pump housing (27) . Remember to align the marks
   that were applied to the mating components.
2. Use two people in order to maneuver plunger (25)
   into spring (26) . Position piston (24) to the
   wear pad that is positioned on the swashplate.
   Tooling (E) will hold the piston in place.
3. When all of the components are aligned, pump head
   (22) should be positioned to pump housing (27) .

Illustration 27
g01071417
Improper assembly of parts that are spring loaded
can cause bodily injury. To prevent possible
injury, follow the established assembly procedure
and wear protective equipment.
27. Install bolts (21) that secure pump head (22)
to the pump assembly. The head is under spring
tension. Install the bolts slowly. Tighten bolts
(21) to a torque of 21 5 Nm (16 4 lb ft).
16

• Illustration 28 g01071365
• Install washer (5) and plug (4) into housing (2)
  .
• Install washer (14) and plug (13) into housing
  (2) .
• Install spool (6) , retainer (7) , spring (8) ,
  spring (9) , and seat (10) .
• Install O-ring seal (12) and plug (11) .
• Install spool (15) , retainer (16) , spring (17)
  , and spring (18) .
• Install plug (19) and O-ring seal (20) .

Illustration 29
g01071364
34. Install O-ring seals (3) and screw (4A) .
17
Illustration 30
g01071362

• Install valve (2) and bolts (1) .
• Fill the pump with hydraulic oil before
  installing the pump to the machine.
• End By Install the piston pump (cushion-hitch).
  Refer to Disassembly and Assembly, "Piston Pump
  (Cushion-Hitch) - Install".

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Rights Reserved. Private Network For SIS
Licensees.
Fri Mar 12 221744 UTC0800 2021
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Product WHEEL SCRAPER Model 621G WHEEL SCRAPER
CEP Configuration 621G Wheel Scraper CEP00001-UP
(MACHINE)
Disassembly and Assembly 621G and 627G Wheel
Tractor-Scrapers Machine Systems Media Number
-RENR4248-01 Publication Date -01/08/2004
Date Updated -09/08/2004
i02326130
Piston Pump (Cushion-Hitch) - Install SMCS -
5070-012 5316-012 Installation
Procedure NOTICE Care must be taken to ensure
that fluids are contained during performance of
inspection, maintenance, testing, adjusting and
repair of the product. Be prepared to collect
the fluid with suitable containers before
opening any compartment or disassembling any
component containing fluids. Refer to Special
Publication, NENG2500, "Caterpillar Tools and
Shop Products Guide" for tools and supplies
suitable to collect and contain fluids on
Caterpillar products. Dispose of all fluids
according to local regulations and mandates.
1. Clean all parts and inspect all parts. If any
parts are worn or damaged, use new parts for
replacement.
19

• Illustration 1 g01055310
• Install the O-ring seal and cushion-hitch pump
  (4). Install the bolts (not shown).
• Connect hose assemblies (1), (2), and (3) .
• Fill the hydraulic tank. Refer to Operation and
  Maintenance Manual, "Refill Capacities".

Copyright 1993 - 2021 Caterpillar Inc. All
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Licensees.
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Product WHEEL SCRAPER Model 621G WHEEL SCRAPER
CEP Configuration 621G Wheel Scraper CEP00001-UP
(MACHINE)
Disassembly and Assembly 621G and 627G Wheel
Tractor-Scrapers Machine Systems Media Number
-RENR4248-01 Publication Date -01/08/2004
Date Updated -09/08/2004
i01999571
Pump Control Valve (Cushion-Hitch) - Remove and
Install SMCS - 5455-010 Removal
Procedure NOTICE Care must be taken to ensure
that fluids are contained during performance of
inspection, maintenance, testing, adjusting and
repair of the product. Be prepared to collect
the fluid with suitable containers before
opening any compartment or disassembling any
component containing fluids. Refer to Special
Publication, NENG2500, "Caterpillar Tools and
Shop Products Guide" for tools and supplies
suitable to collect and contain fluids on
Caterpillar products. Dispose of all fluids
according to local regulations and mandates.
21

• Illustration 1 g01034541
• Remove bolts (2) from pump control valve (1) .
• Remove pump control valve (1) and the gasket from
  cushion-hitch pump (3) .

Installation Procedure NOTICE Keep all parts
clean from contaminants. Contaminants may cause
rapid wear and shortened component life.
1. Clean all parts and inspect all parts. If any
parts are worn or damaged, use new parts for
replacement.
Illustration 2 g01034541 2. Install the gasket
and position pump control valve (1) to
cushion-hitch pump (3) .
22
3. Install bolts (2) .
Copyright 1993 - 2021 Caterpillar Inc. All
Rights Reserved. Private Network For SIS
Licensees.
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Product WHEEL SCRAPER Model 621G WHEEL SCRAPER
CEP Configuration 621G Wheel Scraper CEP00001-UP
(MACHINE)
Disassembly and Assembly 621G and 627G Wheel
Tractor-Scrapers Machine Systems Media Number
-RENR4248-01 Publication Date -01/08/2004
Date Updated -09/08/2004
i02059268
Leveling Valve - Remove SMCS - 5312-011 Removal
Procedure
At operating temperature the implement hydraulic
oil tank is hot and under pressure. Hot oil can
cause burns. To prevent possible injury, release
the pressure in the implement hydraulic system
before hydraulic lines or components are
disconnected or removed.
NOTICE Care must be taken to ensure that fluids
are contained during performance of inspection,
maintenance, testing, adjusting and repair of
the product. Be prepared to collect the fluid
with suitable containers before opening any
compartment or disassembling any component
containing fluids. Refer to Special Publication,
NENG2500, "Caterpillar Tools and Shop Products
Guide" for tools and supplies suitable to collect
and contain fluids on Caterpillar
products. Dispose of all fluids according to
local regulations and mandates.
24
Note Put identification marks on all lines, on
all hoses, on all wires, and on all tubes for
installation purposes. Plug all lines, hoses, and
tubes. This helps to prevent fluid loss and this
helps to keep contaminants from entering the
system. 1. Park the machine on a hard, level
surface. Lower the scraper bowl to the ground and
engage the parking brake. Chock the wheels in
order to prevent the machine from moving.
Illustration 1
g01055452
View from center of the cushion-hitch 2. Move
cable strap (2) away from harness assembly (1).
Remove harness assembly (2) from clip (3).
Disconnect harness assembly (1) .
Illustration 2 g01055453 3. Remove cotter pin
(5) that secures pin (4) to linkage (7). Remove
pin (4) from linkage (7). Move linkage (7) away
from the leveling valve. Disconnect hose assembly
(6) .
25
Illustration 3 g01055455 4. Disconnect hose
assemblies (9), (10), and (11). Disconnect tube
assembly (13). Remove bolts (12) and leveling
valve (8) .
Copyright 1993 - 2021 Caterpillar Inc. All
Rights Reserved. Private Network For SIS
Licensees.
Fri Mar 12 222031 UTC0800 2021
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Product WHEEL SCRAPER Model 621G WHEEL SCRAPER
CEP Configuration 621G Wheel Scraper CEP00001-UP
(MACHINE)
Disassembly and Assembly 621G and 627G Wheel
Tractor-Scrapers Machine Systems Media Number
-RENR4248-01 Publication Date -01/08/2004
Date Updated -09/08/2004
i02560204
Leveling Valve - Disassemble SMCS -
5312-015 Disassembly Procedure Start By A.
Remove the leveling valve. Refer to Disassembly
and Assembly, "Leveling Valve - Remove".
Illustration 1 g01055469 1. Remove locknut (1)
and coil assembly (2) from valve body (3) .
27
Illustration 2
g01281861
Illustration 3
g01281860

1. Remove cartridge assembly (6) from valve body
   (3).
2. Remove O-ring seal (7), O-ring seals (8), and
   backup rings (8A) from cartridge assembly (6).
3. Remove bolts (5) and valve body (3) from housing
   (4) .

28
Illustration 4
g01082306
Personal injury can result from being struck by
parts propelled by a released spring force. Make
sure to wear all necessary protective
equipment. Follow the recommended procedure and
use all recommended tooling to release the
spring force.
5. Remove plugs (10), plugs (9), and the O-ring
seals from valve body (3).
Illustration 5 g01081310 6. Remove spool (13),
spring (12), and O-ring seals (11) from valve
body (3) .
29
Illustration 6
g01082319
Personal injury can result from being struck by
parts propelled by a released spring force. Make
sure to wear all necessary protective
equipment. Follow the recommended procedure and
use all recommended tooling to release the
spring force.

1. Remove retaining ring (14) and lip seal (15) from
   housing (4).
2. Remove bolts (16), cover (17), and the O-ring
   seal from housing (4) .

Illustration 7 g01082330 9. Remove springs (18)
and spool (19) from housing (4) .
30
Illustration 8
g01281830
10. Remove plug (21) and orifices (20) .

• Illustration 9 g01281843
• Remove plug (22) and the O-ring seal from housing
  (4) .
• Remove spool (23) .

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• Illustration 10 g01281844
• Remove bolt (25) and the washers from spool (23).
• Remove fittings (24) and the O-ring seals from
  housing (4) .

Copyright 1993 - 2021 Caterpillar Inc. All
Rights Reserved. Private Network For SIS
Licensees.
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Product WHEEL SCRAPER Model 621G WHEEL SCRAPER
CEP Configuration 621G Wheel Scraper CEP00001-UP
(MACHINE)
Disassembly and Assembly 621G and 627G Wheel
Tractor-Scrapers Machine Systems Media Number
-RENR4248-01 Publication Date -01/08/2004
Date Updated -09/08/2004
i05491852
Leveling Valve - Assemble SMCS -
5312-016 Assembly Procedure NOTICE Keep all
parts clean from contaminants. Contamination of
the hydraulic system with foreign material will
reduce the service life of the hydraulic system
components. To prevent contaminants from entering
the hydraulic system, always plug or cap the
lines, fittings, or hoses as they are
disconnected. Cover any disassembled components
and clean them properly before assembly. Clean
the hydraulic system properly after any major
component exchange or especially after a
component failure, to remove any contamination.
1. Clean all parts and inspect all parts. If any
parts are worn or damaged, use new parts for
replacement. Lubricate the O-ring seals with the
lubricant that is being sealed.
34

• Illustration 1 g01281844
• Install the O-ring seals and fittings (24) into
  housing (4) .
• Install the washers and bolt (25) into spool (23)
  .

Illustration 2
g01281843

1. Install spool (23) into housing (4) .
2. Install the O-ring seal and plug (22) .

35
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