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SZHK Series Oldham Type Cross-shaped Coupling

Home · Products · Coupling / Nut Housing · SZHK Series Oldham Type Cross-shaped Coupling
  • SZHK Series Oldham Type Cross-shaped Coupling
SZHK Series Oldham Type Cross-shaped Coupling

SZHK Series Oldham Type Cross-shaped Coupling

The SZHK series is an Oldham coupling, consisting of two aluminum alloy end hubs with axial grooves and a central cross-shaped engineering plastic (or metal) slider. It achieves pure radial misalignment compensation by the sliding of the central slider within the vertical grooves of the two end hubs, while maintaining backlash-free torque transmission. Its extremely thin axial dimension makes it ideal for precision applications with extremely limited space, such as encoders, miniature stepper motors, and miniature lead screws.

Inquiry
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Technology

The core value of the SZHK Series Oldham Type Cross-shaped Coupling lies in its ability to "be as thin as a cicada's wing, yet cleverly compensate for large eccentricities." Its unique working principle gives it irreplaceable advantages in specific fields.

Performance characteristics SZHK Series Cross-Slide Couplings MH Series Star Couplings Diaphragm Couplings (SMP/DMP)
Core positioning An ultra-compact solution for compensating for large radial misalignment, with zero backlash. General-purpose multi-directional compensation with cost-effective vibration damping. High torque and high-precision multi-directional compensation.
Compensation capability Extremely effective at compensating for radial misalignment (up to +0.5 mm to several millimetres), but offers virtually no compensation for angular misalignment and has limited axial float. Capable of simultaneously compensating for radial, angular and axial movements, offering excellent overall performance. Provides excellent compensation for radial, angular and axial movements simultaneously, with particular strength in angular compensation.
Structural rigidity High torsional rigidity, non-elastic power transmission, zero backlash. Moderate elastic torsional stiffness, with slight cushioning and torsional clearance. Extremely high torsional rigidity and zero backlash.
Structural dimensions Extremely short axial length, making it one of the slimmest types of coupling available. Moderate axial length. Long axial length (particularly in the double-diaphragm type).
Wear and maintenance The intermediate slider is a sliding friction component and is a wear part; it requires regular inspection and replacement (made of engineering plastic). The maintenance interval depends on the magnitude of the misalignment and the rotational speed. The elastomer is a consumable part and requires regular replacement. All-metal construction, with no contact wear and maintenance-free.
Suitable applications Encoder connection, micro-equipment, and slim-profile installations with large radial misalignment. Suitable for connecting servo and stepper motors. High-precision, high-dynamic servo systems.

Main Technical Parameters and Design
1. Structure and Working Principle:
End Hubs: Usually made of aluminum alloy, lightweight, with 90-degree vertical rectangular grooves.
Intermediate Slider: The core component, typically made of engineering plastic (such as POM) or copper alloy. Plastic sliders are lubrication-free, low-noise, and low-inertia; metal sliders have a longer lifespan and are more temperature-resistant, but require lubrication.
Working Principle: The protrusions on both sides of the slider are embedded in the grooves of the two end hubs. When there is radial misalignment between the two shafts, the slider automatically self-aligns by sliding within the two pairs of vertical grooves, thereby transmitting torque.

2. Key Performance and Limitations:
Zero Backlash Transmission: Rigid contact, no elastic elements, ensuring high synchronicity.
Speed ​​Limitation: Due to sliding friction, its maximum allowable speed is usually low, and it is not suitable for high-speed long-term operation, otherwise it will fail due to increased heat generation and wear.
Not Suitable for Angular Misalignment: If angular misalignment exists, point contact or line contact will occur between the slider and the grooves, leading to abnormal wear and jamming.

3. Selection Considerations:
First, confirm that the radial misalignment is within the product's allowable range.
Clearly define the operating speed; it must be within the safe zone of the "speed-misalignment" curve in the product catalog.
Consider the installation space thickness, which is one of its major advantages. Applications
The SZHK series is irreplaceable in areas where spatial constraints and radial misalignment are significant challenges:
Encoders and servo feedback: Connecting servo motor shafts to encoders, compensating for misalignment during installation.
Miniature precision equipment: Micro-drive connections for small instruments, optical instruments, and semiconductor grippers.
Printing and textile machinery: Synchronous transmission between multiple parallel roller shafts with inherent center distance errors.
Any transmission application with extreme limitations on axial installation space.

The SZHK Series Oldham Type Cross-shaped Coupling is a "space magician" and "eccentricity nemesis" in mechanical design. Choosing the SZHK series means you have found an excellent solution in both spatial and radial misalignment dimensions. Although it requires regular maintenance and replacement of the sliders, its performance advantages in its specialized applications are unmatched by other types of couplings. It is a classic and effective tool in the toolbox of precision equipment engineers when dealing with compact layouts and installation errors.

Parameters

Model No. d1/d2 pore size D
(mm)		 L
(mm)		 L1
(mm)		 L2
(mm)		 F
(mm)		 H
(mm)		 Screw size
M		 Tightening torque
(N.m)		 Rated torque
(N.m)		 Maximum torque
(N.m)		 Maximum speed
(RPM)		 Moment of inertia
(kg·m²)		 Static torsional stiffness
(N.m/
rad)		 Permissible eccentricity
(mm)		 Permissible deviation
(° )		 Axial runout
(mm)
Min
(mm)		 Max
(mm)
SZHK-D20*25 4 10 20 25 9.5 6 3 7 M3 1.5 1.5 3 7000 1.5*10-7 60 1.2 3 ±0.2
SZHK-D20*33 4  10  20  33  10  12  3  7  M3 1.5  1.5  3  7000  1.5*10-7 60  1.2  3  ±0.2
SZHK-D25*28 5  12  25  28  10.5  7  3  9.5  M3 1.5  2  4  6100  3.2*10-6 130  1.6  3  ±0.2
SZHK-D25*39 5  12  25  39  11  17  3  9.5  M3 1.5  2  4  6100  3.2*10-6 130  1.6  3  ±0.2
SZHK-D32*45 6  15  32  45  12.5  20  5  11  M4 3.5  5  9  4800  2.6*10-5 275  2  3  ±0.2
SZHK-D34*35 6  17  34  35  13  9  5  11  M4 3.5  5  9  4800  2.8*10-5 275  2  3  ±0.2
SZHK-D40*50 8  20  40  50  15.5  19  5.5  14.5  M5 8  10  20  3600  4.2*10-5 520  2.7  3  ±0.2
SZHK-D44*46 8  22  44  46  15.5  15  5.5  16.5  M5 8  13  26  3600  4.5*10-5 520  3  3  ±0.2
SZHK-D50*58 10  26  50  58  19.5  19  6.5  18.5  M6 13  19  37  3000  1.1*10-4 800  3  3  ±0.2
SZHK-D55*58 10  28  55  58  20.5  17  6.5  21  M6 13  25  50  3000  1.3*10-4 1200  3.2  3  ±0.2
SZHK-D63*71 14  35  63  71  24.5  22  8  23.5  M8 28  33  65  2600  3.5*10-4 1200  3.5  3  ±0.2
SZHK-D70*77 16  37  70  77  26.5  24  8  27  M8 28  56  110  2500  3.5*10-4 1200  4  3  ±0.2

Drawings

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