Loader Bobcat 853, 853H. Manual — part 14
PUMP CAPACITY:
18.0 GPM (68,1 L/min.)
HI FLOW CAPACITY: (Includes )
24.0 GPM (90,8 L/ min.)
at 2750 RPM
C apacity . . . 16.0 Qts (15,1 L)
DISPLACEMENT CONTROL VALVE
N eutral . . . . 310-330 PSI
(2137-2275 kPa)
Stroked . . . . 3O0-320 PSI
(2069-2206 kPa)
HYDRAULIC PUMP
. . . .Gear Type
290 PSI (2000 kPa)
FLOW DIVIDER ADJUSTMENT VALVE
NOTE: Unless otherwise specified
springs have NO significant
pressure value.
HI-FLOW MACHINE
PILOT ACTIVATED DIRECTIONAL
CONTROL VALVE - FLOW CONTROL
SPOOL
FIXED CAPACITY DISPLACEMENT
BIDIRECTIONAL HYDROSTATIC
MOTOR
LEGEND
RESERVOIR:
DIFFERENTIAL PRESSURE SWITCH:
SPRING LOADED FILTER BYPASS
ONE WAY RESTRICTOR VALVE
Printed in U.S.A.
DRIVE MOTOR SHUTTLE VALVE
RELIEF/REPLENISHING VALVE - HIGH
RELIEF VALVE - MAIN:
RELIEF VALVE - PORT:
CHECK VALVE - BUCKET POSITION
VALVE
3500 PSI (24132 kPa)
SOLENOID ACTIVATED DIRECTIONAL
CONTROL VALVE - AUXILIARY
LOAD CHECK VALVE
PILOT ACTIVATED DIRECTIONAL
CONTROL VALVE - UNLOADING
SPOOL
SHUTTLE RELIEF VALVE:
36-44 PSI (248-303 kPa)
1
at Front Quick Couplers
853 (S/N 512811001-15999 WITH JEM AUXILIARY VALVE)
MC2399LU (5-19-99)
2
4
3
5
10
VALVE: 45-55 PSI (311-379 kPa)
6
7
14
13
15
12
9
25
19
20
22
17
16
RELIEF VALVE - CHARGE:
38
31
(Printed June 1999)
PRESSURE:
35 FILTER - HYDROSTATIC (CANISTER)
8 RELIEF VALVE - PORT: (OPTIONAL)
2500 PSI (17238 kPa)
2500 PSI (17238 kPa)
11 RELIEF/ANTICAVITATION VALVE -
PORT (TILT BASE END) (OPTIONAL)
TOW VALVE
18
OPTIONAL . 5000 PSI (34475 kPa)
24
26 MUFFLER (If Equipped)
CHARGE PRESSURE SENSOR
27
28 FLUID TEMPERATURE SENSOR
29
SOLENOID ACTIVATED DIRECTIONAL
CONTROL VALVE - FRONT
AUXILIARY
30
34
36 FILTER - HYDRAULIC (CANISTER)
37
FILTER
COLD OIL BYPASS VALVE
39 ANTICAVITATION VALVE
SOLENOID ACTIVATED DIRECTIONAL
CONTROL VALVE (TWO COIL)
PILOT TO OPEN CHECK VALVE
40
32 RESTRICTION
SYSTEM MAIN RELIEF:
2800 PSI (19306 kPa)
HI FLOW MAIN RELIEF:
3300 PSI (22754 kPa)
STANDARD . 4350 PSI (29990 kPa)
at 1150 PSI (7929 kPa)
RELIEF VALVE - MAIN HIGH FLOW
3000 PSI (20685 kPa)
33 SOLENOID ACTIVATED DIRECTIONAL
CONTROL VALVE
B.O.S.S. L oader - Normally Closed
Standard Loader - Normally Open
140°F. (60°C.) Fluid at Full RPM
CHECK VALVE - FILTER
HYDRAULIC/HYDROSTATIC SCHEMATIC
21 AUXILIARY HYDRAULIC PUMP:
at 1150 PSI (7929 kPa)
at 2750 RPM
6.0 GPM (22,7 L/ min.)
23 CHARGE PUMP . 14.0-15.0 GPM
(52,9-56,7 L/ min.) at 2700 RPM
FILTER
MC2399LU
23
MC2399U (5-19-99)
WORKING CIRCUITS
PILOT PRESSURE
DRAIN CIRCUITS
COMPONENTS
RIGHT DRIVE MOTOR
BUCKET POSITION VALVE (OPTIONAL)
HYDRAULIC
CONTROL
VALVE
FRONT AUXILIARY
OIL
COOLER
D
C
A
B
HYDROSTATIC
FILTER
HYDRAULIC
FILTER
HYDROSTATIC PUMPS
T1LT CYLINDER
LIFT CYLINDER
LEFT DRIVE MOTOR
2
AUXILIARY
SPOOL
TILT CYLINDER
SPOOL
LIFT CYLINDER SPOOL
11
INLET
INLET
OUTLET
OUTLET
1
35
3
26
24
2
3
36
4
40
16
17
16
17
38
38
18
19
19
20
20
22
21
25
8
9
13
13
12
39
5
6
7
10
10
14
AUXILIARY VALVE (JEM)
FRONT AUXILIARY
D1
D2
F1
F2
FEMALE
MALE
FEMALE
MALE
9
15
CASE DRAIN
23
29
29
32
32
34
30
33
31
27
28
PORT
BLOCK
37
Printed in U.S.A.
TROUBLESHOOTING
Chart
The following troubleshooting chart is provided for
assistance in locating and correcting problems which are
most common. Many of the recommended procedures
must be done by authorized Bobcat Service Personnel
only.
W–2004–1285
Check for correct function after adjustments,
repairs or service. Failure to make correct
repairs or adjustments can cause injury or
death.
The hydraulic system will not operate.
1, 2, 3, 5
The transmission warning light comes ON when hydraulics are
operating. (853 Base)
1, 3
Slow hydraulic system action.
1, 3, 4, 5, 6, 8
Hydraulic action is not smooth.
1, 4, 5, 6, 7
Lift arms go up slowly at full engine RPM.
1, 3, 4, 5, 6, 7, 8, 9
The lift arms or Bob–Tach will move the pedal in neutral position.
4
The lift arms come down with the pedal in the neutral position.
4, 9, 10, 11
PROBLEM
CAUSE
KEY TO CORRECT THE CAUSE
1.
The fluid level is not correct.
2.
The pedal linkage is disconnected.
3.
The hydraulic pump has damage.
4.
The pedal linkage is not adjusted correctly.
5.
Relief valve is not at the correct pressure.
6.
Suction leak on the inlet side of the hydraulic pump.
7.
Fluid is cold. Wrong viscosity fluid. (See Section 9.)
8.
Using the loader for more than its rated capacity.
9.
Internal leak in the lift cylinder(s).
10.
External leak from the lift cylinder(s).
11.
Damaged lift spool.
853, 853H Loader
–2–7–
Service Manual
When repairing hydrostatic and hydraulic
systems, clean the work area before
disassembly and keep all parts clean. Always
use caps and plugs on hoses, tubelines and
ports to keep dirt out. Dirt can quickly damage
the system.
I–2003–0888
Tighten Procedures
For tightening torques for hydraulic fittings,
tubelines etc., See Section 9. – Hydraulic Connection
Specifications.
HYDRAULIC SYSTEM INFORMATION
Hydraulic fluid escaping under pressure can
have sufficient force to enter a person’s body
by penetrating the skin. This can cause serious
injury and possibly death if proper medical
treatment by a physician familiar with this
injury is not received immediately.
W–2145–0290
–2–8–
853, 853H Loader
Service Manual
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