205 AND 211 TRACK-TYPE EXCAVATORS Hydraulic System Caterpillar

(P) Pressure line from hydraulic pump(T) Return line to tank(A1) Retract boom cylinders(B1) Extend boom cylinders(A2) Extend bucket cylinder(B2) Retract bucket cylinder(A3) Variable displacement hydraulic motor for left track reverse(B3) Variable displacement hydraulic motor for left track forward(A4) Compound circuit, extend stick cylinder(B4) Compound circuit, retract stick cylinder(X1), (Y1), (X2), (Y2), (X3), (Y3), (X4), (Y4) Control pressure oil

- Cut-in 6.0 bar (600 kPa)

- Cut-out 16.0 bar (1600 kPa)

(3) 4-element valve bank, right, with main relief valve 300 bar (30 000 kPa)

(P) Pressure line from hydraulic pump(T) Return line to tank(A1) Hydraulic swing motor, swing right(B1) Hydraulic swing motor, swing left(A2) Extend stick cylinder(B2) Retract stick cylinder(A3) Variable displacement hydraulic track motor, right track reverse(B3) Variable displacement hydraulic track motor, right track forward(A4) Compound circuit, extend boom cylinders(B4) Compound circuit, extend bucket cylinder(X1), (Y1), (X2), (Y2), (X3), (Y3), (X4), (Y4)

Control pressure oil -

- Cut-in 6.0 bar (600 kPa)

- Cut-out 16.0 bar (1600 kPa)

(4) Pilot control valve (with electrical contact)

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NOTICE

Note the symbols in the operator's compartment. Pilot control valve can be installed for right hand as well as left hand operation, only upon customer's request.

(1) Extend boom cylinders

(2) Retract bucket cylinder

(3) Retract boom cylinders

(4) Extend bucket cylinder

Electrical contact = optional hydraulic function (e.g. grab turning left).

(5) Pilot control valve, right (with electrical contact).

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NOTICE

Installation can possibly be inverted, (see item 4).

(1) Extend stick cylinder

(2) Swing left

(3) Retract boom cylinder

(4) Swing right

Electrical contact = hydraulic optional function (e.g. grab turning right).

(6) Pilot control valve for track motor

LR Left track reverseLV Left track forwardRR Right track reverseRV Right track forward

(6a) Base block with speed and direction pilot control valve.

(6b) Intermediate plate.

(6c) Shuttle valve block with 3/2-way valve.

Connection (B) is oil supply for service brake.

Pilot pressure = 3 bar (300 kPa).

Service pressure = 30 bar (3000 kPa).

(7) 4/2 way valve (electromagnetic operation) for adjusting the track motor intake volume. Variable displacement motor.

(8) Pressure gauge for pilot pressure indication.

(9) Gear pump for hydraulic oil cooler and optional hydraulic function.

(10) 2/2-way valve.

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NOTICE

Stops pilot control pressure when lifting up the left hand armrest of operator's seat. Stops operation for all hydraulic functions except steering and the controls in use.

(11) Control valve bank for cooler circuit without optional hydraulic function.

(11a) Solenoid pressure relief valve for hydraulic oil cooler with electromagnetic control. Pressure setting is 80 bar (8000 kPa), maximum.

(11b) Blank plate

(12) Control valve bank for cooler circuit and optional function.

(12a) Solenoid pressure relief valve for hydraulic oil cooler with electromagnetic control. Pressure setting is 80 bar (8000 kPa) maximum.

(12b) Main relief valves for optional hydraulic function. Pressure setting is 200 bar (20 000 kPa).

(12c) Line relief valves for optional hydraulic function. Pressure setting is 2 x 300 bar (30 000 kPa).

(12d) 4/3-way valve with electromagnetic control. Actuated by pushbutton switches provided in left and right pilot control valves in operator's seat.

(13) Hydraulic motor for fan drive of hydraulic oil cooling system.

(14) Hydraulic oil cooler.

(15) Check valve as ram pressure valve. (Will keep constant oil in return lines at all time.)

(16) Return flow filter with bypass valve.

(17) Hydraulic oil reservoir, pressurized with max. 0.35 bar (35 kPa).

(18) Breather filter (with inlet and discharge valve). Discharge valve opens at max. 0.35 bar (35 kPa). Inlet valve opens at -0.03 bar (-3 kPa) (vacuum).

(19) Treadle brake valve with pressure relief valve. 16 bar (1600 kPa) for swing brake control (205).

(19) Treadle brake valve with pressure relief valve. 16 bar (1600 kPa) for swing brake control (211). Braking force limiter cylinder, controlled through shuttle valve, item 34, and by operating pressure of swing gear motor.

(20) Optional hydraulic function, e.g. hydraulic motor for grab turning, right or left.

(21) Boom cylinders.

(22) Check valve for boom cylinders, with a shutoff valve (to be manually operated from operator's compartment) and a check valve for compound circuit, boom cylinder extension.

(23) Shutoff valve.

a. Shutoff valve for emergency lowering of the boom cylinders.

b. Shutoff valve for pressure switch of overload protection system (if equipped)

(24) Pressure switch of overload protection system (with pressure gauge connection), if equipped.

(25) Bucket cylinder.

(26) Check valve for compound circuit, bucket cylinder extension.

(27) Variable displacement motor with brake valve for the left track.

(27a) Brake valve (sends pilot oil to direction control).

(27b) Adapter plate.

(27c) Hydraulic motor with pressure relief valves at 325 bar (32 500 kPa) and pressure relief valve at 21 bar (2100 kPa) for intake volume adjustment.

(27d) Track brake.

(28) Constant displacement axial piston swing motor with built-in main relief valves.

2 x 210 bar (21 000 kPa) (211)

2 x 250 bar (25 000 kPa) (205)

(29) Stick cylinder.

(30) Check valve for stick cylinder.

(31) Variable displacement motor with brake valve for right track.

(31a), (31b), (31c), (31d) See item 27.

(32) Forward flow filter with bypass valve.

(33) Restrictor orifice for track motor protection against torque spikes, 1.0 bar (100 kPa).

(34) Shuttle valve for pilot pressure to the braking force limiter (item 19).

(35) Electrical toggle switch with indicator light. Actuating 4/2-way valve (item 7) and adjusting intake volume of track motors.