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Hyundai Excavator R450LC-7. Service and repair manual - page 22

7-14

Unit : kgf

CONTROL LEVER OPERATING FORCE

Use a spring scale to measure the
maximum resistance of each control lever
at the middle of the grip.

Preparation

Keep the hydraulic oil temperature at
50

。

easurement

Start the engine.
Select the following switch positions.

Mode selector : H mode

Operate each boom, arm, bucket and
swing lever at full stroke and measure the
maximum operating force for each.
Lower the bucket to the ground to raise
one track off the ground. Operate the
travel lever at full stroke and measure the
maximum operating force required.
When finished, lower the track and then
jack-up the other track.
Repeat steps

③

and

④

three times and

calculate the average values.

valuation

11)

(1)

(2)

①

(3)

①
②

③

④

⑤

The measured operating force should be within the following specifications.

(

7-15

Unit : mm

CONTROL LEVER STROKE

Measure each lever stroke at the lever top
using a ruler.
When the lever has play, take a half of
this value and add it to the measured
stroke.

Preparation
Keep the hydraulic oil temperature at
50

。

easurement

Stop the engine.
Measure each lever stroke at the lever
top from neutral to the stroke end using a
ruler.
Repeat step

②

three times and calculate

the average values.

Evaluation

12)

(1)

※

(

(3)

①
②

③

The measured drift should be within the following specifications.

(

Model

R450LC-7

Kind of lever

Boom lever

Arm lever

Bucket lever

Swing lever

Travel lever

Standard

142

Maximum allowable

109

178

Remarks

7-16

PILOT PRIMARY PRESSURE(~#0464)

Preparation

Stop the engine.
Remove the top cover of the hydraulic
tank oil supply port with a wrench.
Loosen and remove plug on the pilot
pump delivery port and connect pressure
gauge.
Start the engine and check for oil
leakage from the port.
Keep the hydraulic oil temperature at
50

。

easurement

Select the following switch positions.

Mode selector : H mode

Auto decel switch : OFF

Measure the primary pilot pressure in the
H mode.

valuation

13)

(1)

(2)

①

②

①
②

③

④

⑤

The average measured pressure should meet the following specifications:

Unit : kgf / cm

(3)

Model

R450LC-7

Engine speed

H mode

Standard

Allowable limits

Remarks

45077MS01

7-16-1

PILOT PRIMARY PRESSURE(#0464~)

Preparation

。

easurement

Select the following switch positions.

Mode selector : M mode

Auto decel switch : OFF

Measure the primary pilot pressure in the
H mode.

valuation

13)

(1)

(2)

①

②

①
②

③

④

⑤

The average measured pressure should meet the following specifications:

Unit : kgf / cm

(3)

Model

R450LC-7

Engine speed

M mode

Standard

Allowable limits

Remarks

50077MS01

7-17

Preparation

Stop the engine.
Remove the top cover of the hydraulic
tank oil supply port with a wrench.
Push the pressure release button to
bleed air.
To measure the speed selecting pressure:
Install a connector and pressure gauge
assembly to turning joint P port as shown.
Start the engine and check for on
leakage from the adapter.
Keep the hydraulic oil temperature at
50

。

easurement

Select the following switch positions.
Travel mode switch : 1 speed

2 speed

Mode selector : H mode

Measure the travel speed selecting
pressure in the Hi or Lo mode.
Lower the bucket to the ground to raise
the track off the ground. Operate the
travel lever at full stroke and measure the
fast speed pressure.
Repeat steps

②

and

③

three times and

calculate the average values.

valuation

FOR TRAVEL SPEED SELECTING PRESSURE

(1)

①
②

③

④

⑤

⑥

(

①

②

③

④

The average measured pressure should be within the following specifications.

Unit : kgf / cm

(3)

Model

R450LC-7

Travel speed mode

1 Speed

2 Speed

Standard

Maximum allowable

Remarks

45077MS02

7-18

Preparation

Stop the engine.
Remove the top cover of the hydraulic
tank oil supply port with a wrench.
The pressure release L wrench to bleed
air.
Install a connector and pressure gauge
assembly to swing motor SH port, as
shown.
Start the engine and check for oil
leakage from the adapter.
Keep the hydraulic oil temperature at
50

。

easurement

Select the following switch positions.

Mode selector : H mode

Operate the swing function or arm roll in
function and measure the swing brake
control pressure with the brake
disengaged. Release the control lever to
return to neutral and measure the control
pressure when the brake is applied.
Repeat step

②

three times and calculate

the average values.

valuation

(1)

①
②

③

④

⑤

⑥

(

①

②

The average measured pressure should be within the following specifications.

Unit : kgf / cm

WING PARKING BRAKE RELEASING PRESSURE

15)

(3)

Model

R450LC-7

Description

Brake disengaged

Brake applied

Standard

Allowable limits

22~50

Remarks

45077MS03

7-19

Preparation

Stop the engine.
Remove the top cover of the hydraulic
tank oil supply port with a wrench.
Push the pressure release button to
bleed air.
To measure the main pump pressure.
Install a connector and pressure gauge
assembly main pump gauge port as
shown.
Start the engine and check for oil
leakage from the port.
Keep the hydraulic oil temperature at
50

。

easurement

Select the following switch positions.

Mode selector : H mode

Measure the main pump delivery
pressure in the H mode(High idle).

Evaluation

16)

(1)

(2)

①

②

①
②

③

④

⑤

⑥

The average measured pressure should meet the following specifications.

Unit : kgf / cm

Model

R450LC-7

Engine speed

High ilde

Standard

Allowable limits

Remarks

(

45077MS04

MAIN PUMP DELIVERY PRESSURE(~#0463)

7-19-1

Preparation

。

easurement

Select the following switch positions.

Mode selector : M mode

Measure the main pump delivery
pressure in the M mode(High idle).

Evaluation

16)

(1)

(2)

①

②

①
②

③

④

⑤

⑥

The average measured pressure should meet the following specifications.

Unit : kgf / cm

Model

R450LC-7

Engine speed

High ilde

Standard

Allowable limits

Remarks

(

36077MS03

MAIN PUMP DELIVERY PRESSURE(#0464~)

7-20

Preparation

Stop the engine.
Remove the top cover of the hydraulic
tank oil supply port with a wrench.
Push the pressure release button to
bleed air.
To measure the system relief pressure.
Install a connector and pressure gauge
assembly main pump gauge port, as
shown.
Start the engine and check for oil
leakage from the port.
Keep the hydraulic oil temperature at
50

。

easurement

Select the following switch positions.

Mode selector : H mode

Slowly operate each control lever of
boom, arm and bucket functions at full
stroke over relief and measure the
pressure.
In the swing function, place bucket
against an immovable object and
measure the relief pressure.
In the travel function, lock undercarriage
with an immovable object and measure
the relief pressure.

Evaluation

(1)

①
②

③

④

⑤

⑥

(

①

②

③

④

The average measured pressure should be within the following specifications.

Unit : kgf / cm

( ) : Power boost

YSTEM PRESSURE REGULATOR RELIEF SETTING(~#0463)

17)

(3)

Model

R450LC-7

Function to be tested

Boom, Arm, Bucket

Travel

Swing

Standard

330(360)

345

285

Maximum allowable

390

45077MS04

7-20-1

Preparation

。

easurement

Select the following switch positions.

Mode selector : M mode

Evaluation

(1)

①
②

③

④

⑤

⑥

(

①

②

③

④

The average measured pressure should be within the following specifications.

Unit : kgf / cm

( ) : Power boost

YSTEM PRESSURE REGULATOR RELIEF SETTING(#0464~)

17)

(3)

Model

R450LC-7

Function to be tested

Boom, Arm, Bucket

Travel

Swing

Standard

330(360)

345

285

Maximum allowable

390

36077MS03

7-22

2. MAIN CONTROL VALVE

Part name

Inspection item

Criteria & measure

Existence of scratch, rusting or corrosion.

Existence of scratch, gnawing, rusting or
corrosion.

O-ring seal sections at both ends.

Insert spool in casing hole, rotate and
reciprocate it.

Damage of poppet or spring

Insert poppet into casing and function it.

Rusting, corrosion, deformation or breaking
of spring, spring seat, plug or cover.

External oil leakage.

Rusting, corrosion or deformation of seal
plate.

External rusting or damage.

Contacting face of valve seat.

Contacting face of poppet.

Abnormal spring.

O-rings, back up rings and seals.

In case of damage in following section,
replace part.

- Sliding sections of casing fore and

spool, especially land sections applied
with holded pressure.

- Seal pocket section where spool is inserted.

- Seal section of port where O-ring contacts.

- Seal section of each relief valve for

main, travel, and port.

- Other damages that may damage

normal functions.

Replacement when its outside sliding
section has scratch(Especially on seals-
contacting section).

Replacement when its sliding section has
scratch.

Correction or replacement when O-ring is
damaged or when spool does not move
smoothly.

Correction or replacement when sealing
is incomplete.

Normal when it can function lightly
without being caught.

Replacement for significant damage.

Correction or replacement.

Replacement.

Replacement when damaged.

Replacement.

100

replacement in general.

Casing

Spool

Poppet

Around spring

Around seal
for spool

Main relief valve,
port relief valve &
negative control
relief valve

7-24

4. RCV LEVER

Criteria

Remark

The valve is to be replaced when the leakage

becomes more than 1000cc/m at neutral handle

position, or more than 2000cc/m during operation.

This is to be replaced when the sliding surface

has worn more than 10

m, compared with the

non-sliding surface.

This is to be replaced when the top end has worn

more than 1mm.

The pin, shaft, and joint of the operating section

are to be replaced when their plays become more

than 2mm due to wears or so on.

When abnormal noises, hunting, primary pressure

drop, etc. are generated during operation, and

these cannot be remedied, referring to section 6.

Troubleshooting, replace the related parts.

Leakage

Spool

Push rod

Play at operating

section

Operation stability

Conditions :

Primary pressure : 30kgf/cm

Oil viscosity : 23cSt

The leakage at the left condition is

estimated to be nearly equal to the

above leakage.

When a play is due to looseness of

a tightened section, adjust it.

Maintenance

check item

Notes 1. It is desirable to replace seal materials, such as O-rings, every disassembling. However,

they may be reused, after being confirmed to be free of damage.

2. When loosening the hexagon socket head cap screw(125), replace the seal washers(121)

without fail.

Content .. 20 21 22 23 ..