213 TRACK-TYPE EXCAVATOR Hydraulic Circuit Caterpillar

Fig. WH 194

NOTE: 1 Bar is equal to 100 kPa; 1 Bar is equal to 14.5 psi; 1 psi is equal to 6.9 kPa.

(1) Variable double pump with total capacity controller

(2) 4-element valve bank left with 300 bar (30 000 kPa) main relief valve

Connections:

(P) Pressure line from hydraulic pump

(T) Return line to tank

(A1) Retract bucket cylinder

(B1) Extend bucket cylinder

(A2) Retract boom cylinders

(B2) Extend boom cylinders

(A3) Hydraulic motor for running gear - left-forward

(B3) Hydraulic motor for running gear - left-reverse

(A4) Series connection, extend stick cylinder and e.g. rotate grab

(B4) e.g. rotate grab

(X1), (Y1), (X2), (Y2), (X3), (Y3) Pilot pressure oil -

- cut-in 6.5 bar (650 kPa)

- cut-out 15 bar (1500 kPa)

(X4), (Y4) Pilot pressure oil -

- cut-in 18 bar (1800 kPa)

- cut-out 26 bar (2600 kPa)

See also topic, Spring Installation for the 4th section of left valve bank.

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

Connections:

(P) Pressure line from hydraulic pump

(T) Return line to tank

(A1) Hydraulic motor for swing gear - CCW swing

(B1) Hydraulic motor for swing gear - CW swing

(A2) Extend stick cylinder

(B2) Retract stick cylinder

(A3) Hydraulic motor for running gear - right-forward

(B3) Hydraulic motor for running gear - right-reverse

(A4) Series connection extend bucket cylinder

(B4) Series connection extend boom cylinders

(X1), (Y1), (X2), (Y2), (X3), (Y3) Pilot pressure oil -

- cut-in 6.5 bar (650 kPa)

- cut-out 15 bar (1500 kPa)

(X4), (Y4) Pilot pressure oil -

- cut-in 18 bar (1800 kPa)

- cut-out 26 bar (2600 kPa)

(4) Pilot control valve, left (with electric contact)

Connections:

(A1) Retract stick cylinder

(A2) CW swing

(B1) CCW swing

(B2) Extend stick cylinder

(5) Pilot control valve, right

Connections:

(A1) Retract boom cylinders

(A2) Retract bucket cylinder

(B1) Extend bucket cylinder

(B2) Extend boom cylinders

(6) 4-way electromagnetic directional valve

a. In the pilot control lines for CW swing and series connection stick cylinder, or for optional hydraulic attachment function (e.g. rotate grab CW). Controlled by electric contact of pilot control valve, right, Item 5.

b. In the pilot control lines for CCW swing or for optional hydraulic attachment function (e.g. rotate grab CCW). Controlled by electric contact of pilot control valve, right, Item 5.

c. In the pilot control of the line to the multi-disc brakes of the running gear, solenoid valve energized brakes released; solenoid valve de-energized = brakes engaged. The solenoid valve itself is controlled by the electric contact of the central pilot control valve, Item 23. Pressing the electric contact causes the solenoid valve to take up one switch position, pressing it again causes the valve to take up another switch position (relay circuit).

(7) Bucket cylinder

(8) Boom cylinder

(9) Axial piston fixed displacement motor for running gear-left

(10) Axial piston fixed displacement motor for swing gear

(11) Stick cylinder

(12) Axial piston fixed displacement motor for running gear-right

(13) Cut-off valve for boom cylinders (operated from driver's cab)

(14) Throttle check valve for boom cylinders

(15) Throttle check valve for stick cylinder

(16) Hydraulic oil cooler

(17) Check valves used as back-pressure valves

(18) Return filter with bypass valve

(19) Cut-off valve in service hydraulic circuit, stick cylinder series connection:

Cut-off valve open - stick cylinder series connection

Cut-off valve closed - for optional hydraulic function, e.g. rotate grab

(20) Optional hydraulic function, e.g. rotate hydraulic motor for grab with line relief valves

(21) Cut-off valve in the pilot control line

Cut-off valve open - stick cylinder series connection

Cut-off valve shut - for optional hydraulic function, e.g. rotate grab

(22) Check valve

a. For bucket cylinder, series connection

b. For boom cylinders, series connection

(23) Pilot control valve, center

Connections:

(A1) Left track forward (right curve)

(A2) Right track reverse

(B1) Right track forward (left curve)

(B2) Left track reverse

(B1/B2) Rotate left

(A1/A2) Rotate right

(24) Hydraulic pressurization valve

Controlled by pilot control valve, item 23, during forward and reverse travel only. Activated by pilot control pressure, a back pressure of 30 bar (3000 kPa) develops in the return line system of the lefthand valve bank. With this aid, the oil level of the axial piston fixed displacement motor for the running gear is maintained (anticavitation effect). The 30 (3000 kPa) bar return line back pressure prevails only as long as the oil pressure of the axial piston fixed displacement motor is less than 70 bar (7000 kPa) (downhill running). When the pressure is greater than 70 bar (7000 kPa), the back pressure function of the pressurization valve is cut out by the high pressure.

(25) Hydraulic shuttle, valve in pilot control circuit for forward and reverse travel for left and right and pressurization valve (total of 3 units).

(26) Breather filter (with inlet and discharge valve)

Inlet valve opens at max. 0.35 bar (35 kPa)

Discharge valve opens at -0.03 bar (3 kPa)

(27) Hydraulic oil reservoir, presurrized at max. 0.35 bar (35 kPa)

(28) Cut-off valve

a. Cut-off valve for emergency lowering of boom cylinders

b. Cut-off valve for overload warning pressure switch, (if equipped)

(29) Pressure switch for overload warning device (with pressure gauge connection), when equipped.