EX355
T3-5-9
TRAVEL DEVICE
When traveling:
Pressure oil from the control valve enters port BV,
flows around spool CB in the counterbalance valve,
opens check valve BC, and flows into port BM. On the
other hand, the return oil from the travel motor is routed
to port AM. However, the circuit is blocked by check
valve AC and spool CB. Oil pressure in port BV is
routed into chamber G via orifice F of spool CB so that
when oil pressure in port BV increases further, spool
CB is moved to the left.
Then, the return oil from the travel motor flows to port
AV via notch H on spool CB. Thus, pressure oil flows
through the circuit , enabling the travel motor to rotate.
When the travel control lever is returned to neutral,
spool CB is returned to the original position by spring
force, blocking the oil circuit. Thereby, the travel motor
stops rotating.
When descending:
While descending a slope, the travel motor is forcibly
rotated by the machine weight (pump operation). When
the travel motor starts sucking pressure oil, oil pres-
sure in port BV and chamber G is reduced, moving
spool CB to the right. Then, the return oil flow from the
travel motor is restricted, increasing oil pressure in
port AM. Therefore, the travel motor is braked. Once
the oil flow is restricted, oil pressure in port BV
increases again, moving spool CB to the left.
This operation (hydraulic brake operation) is repeated
so that machine runaway is prevented.
Circuit Protection:
When circuit pressure increases more than the set
pressure of the overload relief valve, the valve opens,
allowing high pressure oil to relieve to the lower
pressure side.
Thereby, the travel motor is protected from overloads.
The valve also functions to relieve shock pressure
developed when the travel motor stops.
If the travel motor draws oil due to pump operation,
check valve BC is unseated (makeup operation) so
that cavitation is prevented.
SM5011
Overload relief valve
Check valve AC
Spool CB
Check valve BC
Overload relief valve
BM
AM
AV
BV
H
F
G
Summary of Contents for EX355 Tier2
Page 22: ...T1 2 10 EX355 COMPONENT LAYOUT NOTES ...
Page 37: ...T2 1 14 EX355 CONTROL SYSTEM NOTES ...
Page 47: ...T2 2 10 EX355 HYDRAULIC SYSTEM NOTES ...
Page 73: ...T2 3 26 EX355 ELECTRICAL SYSTEM NOTES ...
Page 86: ...T3 1 12 EX355 PUMP DEVICE NOTES ...
Page 94: ...T3 2 8 EX355 SWING DEVICE NOTES ...
Page 134: ...T3 4 10 EX355 PILOT VALVE NOTES ...
Page 146: ...T3 5 12 EX355 TRAVEL DEVICE NOTES ...
Page 156: ...T3 7 4 EX355 OTHER COMPONENTS Undercarriage NOTES ...
Page 195: ...T4 2 6 EX355 STANDARD NOTES ...
Page 199: ...T4 3 4 EX355 ENGINE TEST NOTES ...
Page 215: ...T4 4 16 EX355 EXCAVATOR TEST NOTES ...
Page 237: ...T4 5 22 EX355 COMPONENT TEST NOTES ...
Page 265: ...T5 2 12 EX355 COMPONENT LAYOUT NOTES ...
Page 325: ...T5 4 52 EX355 TROUBLESHOOTING B ...
Page 372: ...EX355 T5 6 9 ELECTRICAL SYSTEM INSPECTION ...
Page 385: ...T5 6 22 EX355 ELECTRICAL SYSTEM INSPECTION NOTE ...
Page 425: ...W1 1 4 EX355 PRECAUTIONS FOR DISASSEMBLY AND ASSEMBLY NOTES ...
Page 450: ...W2 3 8 EX355 MAIN FRAME NOTES ...
Page 454: ...W2 4 4 EX355 PUMP DEVICE SM5510 ...
Page 456: ...W2 4 6 EX355 PUMP DEVICE SM5510 ...
Page 458: ...W2 4 8 EX355 PUMP DEVICE ASSEMBLE PUMP DEVICE SM6205 SM6206 ...
Page 460: ...W2 4 10 EX355 PUMP DEVICE SM6205 SM6206 ...
Page 462: ...W2 4 12 EX355 PUMP DEVICE SM6205 SM6206 ...
Page 464: ...W2 4 14 EX355 PUMP DEVICE SM6205 SM6206 ...
Page 468: ...W2 4 18 EX355 PUMP DEVICE SM6210 ...
Page 470: ...W2 4 20 EX355 PUMP DEVICE SM6210 ...
Page 472: ...W2 4 22 EX355 PUMP DEVICE SM6210 ...
Page 474: ...W2 4 24 EX355 PUMP DEVICE SM5511 SM6219 ASSEMBLE MAIN PUMP ...
Page 476: ...W2 4 26 EX355 PUMP DEVICE SM5511 SM6219 ...
Page 478: ...W2 4 28 EX355 PUMP DEVICE SM5511 SM6219 ...
Page 480: ...W2 4 30 EX355 PUMP DEVICE SM5511 SM6219 ...
Page 482: ...W2 4 32 EX355 PUMP DEVICE SM5511 SM6219 ...
Page 484: ...W2 4 34 EX355 PUMP DEVICE SM5511 SM6219 ...
Page 486: ...W2 4 36 EX355 PUMP DEVICE SM5511 SM6219 ...
Page 498: ...W2 4 48 EX355 PUMP DEVICE NOTES ...
Page 532: ...W2 5 34 EX355 CONTROL VALVE NOTES ...
Page 540: ...W2 6 8 EX355 SWING DEVICE SM6277 31 18 17 20 19 21 3 24 27 25 26 10 ...
Page 542: ...W2 6 10 EX355 SWING DEVICE SM6277 31 19 2 1 23 22 ...
Page 566: ...W2 7 12 EX355 PILOT VALVE 11 19 17 18 1 2 3 8 13 14 16 15 SM1114 ...
Page 572: ...W2 7 18 EX355 PILOT VALVE 8 6 7 1 3 4 5 9 21 2 SM1119 ...
Page 586: ...W2 7 32 EX355 PILOT VALVE NOTES ...
Page 592: ...W2 8 6 EX355 PILOT SHUT OFF VALVE NOTES ...
Page 602: ...W2 10 6 EX355 SOLENOID VALVE UNIT NOTES ...
Page 621: ...W3 2 10 EX355 TRAVEL DEVICE SM5108 44 8 13 12 1 45 46 28 27 25 26 24 36 38 30 31 32 ...
Page 627: ...W3 2 16 EX355 TRAVEL DEVICE SM5502 3 4 5 20 7 8 9 10 12 14 13 16 11 6 ...
Page 643: ...W3 2 32 EX355 TRAVEL DEVICE NOTES ...
Page 651: ...W3 3 8 EX355 CENTER JOINT NOTES ...
Page 655: ...W3 4 4 EX355 TRACK ADJUSTER 8 14 13 11 17 12 SM6284 ...
Page 657: ...W3 4 6 EX355 TRACK ADJUSTER 3 4 8 10 16 15 14 SM6284 ...
Page 659: ...W3 4 8 EX355 TRACK ADJUSTER 3 6 4 8 10 9 SM6284 18 ...
Page 667: ...W3 4 16 EX355 TRACK ADJUSTER NOTES ...
Page 671: ...W3 5 4 EX355 FRONT IDLER 1 SM6290 2 4 3 5 6 8 12 7 6 3 4 1 2 9 10 11 ...
Page 689: ...W3 6 14 EX355 UPPER AND LOWER ROLLER NOTES ...
Page 708: ...W4 1 10 EX355 FRONT ATTACHMENT NOTES ...
Page 716: ...W4 1 18 EX355 FRONT ATTACHMENT NOTES ...
Page 744: ...W4 2 28 EX355 CYLINDERS NOTES ...
Page 763: ...EX355 W5 1 17 GENERAL INFORMATION Oil Pan N m kgf m Ib ft SM7010 ...
Page 765: ...EX355 W5 1 19 GENERAL INFORMATION Water Pump N m kgf m Ib ft SM7012 ...
Page 815: ...EX355 W5 3 35 ENGINE OVERHAUL Disassembly SM7093 1 Camshaft gear 2 Knock pin 3 Camshaft ...
Page 883: ...EX355 W5 3 103 ENGINE OVERHAUL Reassembly 1 Crankshaft 3 Crankshaft gear 2 Pin SM7239 ...
Page 894: ...W5 3 114 EX355 ENGINE OVERHAUL NOTE ...
Page 938: ...W5 7 6 EX355 ENGINE INDUCTION NOTE ...