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Home->Products->Hydraulic motors->Hydraulic steering units->Model BZZ1/BZZ2/BZZ3 Hydraulic Steering Control Units (SCU)

Model BZZ1/BZZ2/BZZ3 Hydraulic Steering Control Units (SCU)

BZZ series hydraulic steering unit is consisted of one pair of rotary valve and one pair of gerotor. Via the steering column, the steering unit links the steering wheel, when the steering wheel rotates, the oil flows out of the supply pump of the steering system , through the rotary valve and the gerotor , to the cylinder’s port left or right ( depend upon the rotation direction). The gerotor supplies the oil to the steering cylinder in proportion to the angular rotation of the steering wheel. If the oil flow out of the supply pump of the steering system is too small, the
steering unit can work as the manual pump.

Characteristic Features:
SCU can be used in the area of steering of vehicle and hydraulic rudder of ships where the operator can use it to control power steering force with light operating force. It is safety, reliable and smooth in the function and operation.
Model BZZ1/BZZ2/BZZ3 offer the following advantages:
    Eliminate linkage-reduce cost, provide flexibility in design
    Provide operator comfortable
    Automatically reverts to emergency manual pump in case of engine failure
    Provide continuous unlimited control circuits and meter sizes
    Can work with many kinds of power steering pumps or fluid supply systems.

Order Code:


①: Cycloid Rotary Valve Hydraulic Steering Units;
②: Function Code:
      1:Open center non-reaction
      2:Open center reaction
      3:Closed center non-reaction
      5:Load sensing
③: Pressure grade 16MPa;
④: Displacement;
⑤: Mounting Data:
      A:Long spigot, cross-block mounting
      B:SAE involute spline mounting
      C:Short spigot, cross-block mounting;
⑥: Code for special characteristics;
⑦: Ports Code;
⑧: Code for other requirements.

Function Code:

Open Center Non-Reaction

Open Center Reaction

Closed Center Non-Reaction

Main Specifications:

Type Displacement
(mL/ r)
pressure (MPa)
Max. cont. back
pressure (MPa)
BZZ囗  –E50 * 50 4 16 2.5 4.72
BZZ囗  –E63 * 63 5 4.85
BZZ囗  –E80 * 80 6 5
BZZ囗  –E100 * 100 7.5 5.27
BZZ囗  –E125 * 125 9.5 5.43
BZZ囗  –E160 * 160 12 5.75
BZZ囗  –E200 * 200 15 6.08
BZZ囗  –E250 * 250 19 6.48
BZZ囗  –E280 * 280 21 6.78
BZZ囗  –E315 * 315 24 7.13
BZZ囗  –E400 * 400 30 7.78
BZZ囗  –E500 * 500 38 8.67
BZZ囗  –E630 * 630 48 9.72
BZZ囗  –E800 * 800 60 11.18
BZZ囗  –E1000 * 1000 75 12.8

Note 1: 囗 represents Function Code, BZZ2 can be chosen for SCU with the displacement of 50-200mL/r. BZZ1 or BZZ3 can be chosen for SCU with the displacement of 50-1000mL/r.
Note 2: "Flow" that we suggest to use is the flow of 1.25 times as much as that at the steering wheel's rotation speed of 60 r/min. If the design of the system can't meet the requirements, the flow is allowed to be adjusted a little bit.

Mounting Data:

Note 1: Above is for Short ringed boss connection dimension. When dimension is 18, 25, 30.5, instead of 9,16,19.5 Long ringed boss connection is available for reference above.
Note 2: please check below for the port code.

Characteristic Code:

Code Definition Remark
(omit) Common Type Fit various steering system, e.g. tractor, loader, and road roller, etc. mainly used in china.
D Input torque:
1.6N·m~2.4 N·m
fit steering system of vehicles that driving on flat road, such as forklift.
C Input torque:
Codes for the requirement of other performance characteristics (should be confirmed in an agreement) e.g. manual steering, lower terminal steering feeling, noise and back-to-the-neutral-position function etc., or comprehensive requirement.

Port threads:

Code Ports P,T,A,B Column Mounting C Valve Mounting V
(omit) M20×1.5 M10 M12
A M18×1.5 M10 M12
B G1/2 M10 M10×1
C 3/4-16UNF O-ring 3/8-16UNC 3/8-24UNF
D M20×1.5 O-ring M10 M12
E M18×1.5 O-ring M10 M12
G M22×1.5 M10 M12
Q M22×1.5 O-ring M10 M12
U G1/2 O-ring M10 M10×1
M 3/4-16UNF O-ring M10 M12
I 3/4-16UNF O-ring M10 M10
N 3/4-16UNF O-ring M10×1.25 M10
R P,T:M22×1.5 M10 M12
S P,T:M22×1.5 O-ring M10 M12
A,B:M18×1.5 O-ring
Other requirements:
Mainly refers to the appearance, paint color etc. specified by agreement; the code will be listed in the agreement.

Note 1: Ports P,T,A,B Depth : 14 mm; Column Mounting C & V Depth: 16 mm.


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