214 & 224 WHEEL-TYPE EXCAVATORS Swivel (7-way and 3 + 2-way) Caterpillar

Swivel (7-way and 3 + 2-way)

Fig. WH 121

The hydraulic and pneumatic energies between the rotating upper carriage and the stationary undercarriage are transmited through the hydraulic rotating joints.

(1) 7-way hydraulic rotating joint


(0) Leak oil

(1) Reverse travel

(2) Raise lower chasis stabilizer or grader

(3) Forward travel

(4) Extend lower chassis stabilizer or grader

(5) Retract steering cylinder - right turn

(6) Extend steering cylinder - left turn

Seven independent oil ducts lead from the upper to the lower carriage. Stator B is fixed to the lower chassis in the center of rotation of the upper carriage. The hydraulic lines link the stator connections to the actuators listed. The rotor C is mounted on the stator and is rotated by a driver on the upper chassis. The pressurized oil flows through the rotor connections to the various circular channels, which are sealed off against each other. Oil reaches the vertical oil channels through the individual superposed holes and the connections in the lower part of the stator through transverse holes.

NOTE: The incidental leak-oil lubricates simultaneously. For this reason the leak-oil channel should be filled after assembly. Bleed all other lines.

(2) 3 + 2-way pneumatic-hydraulic rotating joint accessory

Tighten plug to 40 N·m, apply "Loctite pipe sealer, strong grade" when inserting.

(3) Fill opening between rotor and stator housing with Molykote BR2 Universal Heavy Duty Grease.

Connections for Stator D

(1) Parking brake (pressure = release)

(2) Swing axle valve (venting = block)

(3) Service brake (pressure = brake)

(4) Venting

(5) High-ratio powershift gearbox

Connections for Connecting Piece Q

(1) Parking brake (pressure = release)

(2) Swing axle valve (venting = block)

(3) Service brake (pressure = brake)

(4) High-ratio powershift gearbox

(5) Low-ratio powershift gearbox

Connections 1, 2 and 3 are subjected to pneumatic pressure. Connections 5, 6 (in the stator above) or 4, 5 (in the connection piece below) are subjected to hydraulic pressure. Connection 4 (in the stator) is for venting and serves as a partition between air and oil.

Rotor E, mounted in casing (stator) D, is held in the direction of the axis by cap F. Connection screw G is held in place by bracket H. Special sealing elements seal off the circular chambers J. Each chamber is connected to an axial hole K and a radial threaded connection L and also via intermediary pieces M and N to a threaded connection P in connecting piece Q. The axial holes K are sealed off between rotor E and intermediary piece M by washer R, in the case of intermediary piece N and connecting piece Q by washer S.

Prior to fitting the attachment onto the 7-way hydraulic rotating joint, connecting piece Q must be removed by loosening screw T. Then the rotating joint with the lower part of the rotor (intermediary piece M/N) is fitted through the hole in the center of the 7-way rotating joint and fastened to the cover. Subsequently, connecting piece Q with washer S is screwed back onto intermediary piece N from below.

Thanks to the fixing pin provided, the numbered lines can not be confused. The lines are connected by threaded unions.

Not Shown:

Casing D is made to rotate with the upper carriage by means of driver pins. In order to avoid deformation of the rotary connections, special care should be taken during assembly that there is sufficient play between the hole in the casing flange and the upper carriage pin. For the same reason, the lines should be connected to the casing with hose connectors.


(1) = 15 - 20 N·m

Grease O-rings and O-ring grooves with Molykote BR Universal Heavy Duty Grease.

Area A:

Do not use BR 2 grease here. Oil the sealing elements with the specified hydraulic fluid.