Description
The SHAC QK and QB Series pneumatic linear guide rail clamps hold a stationary machine axis directly on the free surfaces of a compatible profile rail. Direct rail clamping helps maintain position, increase local rigidity and reduce the static holding load carried by the ball screw, belt, rack, coupling, gearbox or motor brake.
The two series differ in their default state. The QK Series is normally open: the clamp is released without air and closes when compressed air is supplied. The QB Series is normally closed: spring force applies the clamp when air is absent, while compressed air releases it for axis movement. This pressure-loss behaviour makes the QB Series suitable for applications where the axis should remain held after loss of pneumatic pressure, subject to the machine designer’s verified safety calculation.
QK Series – Normally Open Dimensions and Technical Data
The drawing and supplier table below apply to the QK Series. Dimensions are in millimetres. The selectable QK variants on this product page are GH20QK, GH25QK and GH30QK; the additional GH35QK and GH45QK rows are retained as supplier reference data.
| Model No. | SKU | W | WR | H | H1 | H2 | L | B | C | C1 | M × L1 | E | D1 | D2 | Holding Force (N) | Air Consumption (L/cycle) | Weight (kg) |
| GH20QK | 1260001 | 66 | 20 | 30 | 4.5 | / | 39 | 20 | 20 | 9.5 | M5 × 6 | 5 | 4.5 | 14.5 | 1,000 | 0.018 | 0.33 |
| GH25QK | 1260002 | 75 | 23 | 36 | 5.5 | 42 | 39 | 20 | 20 | 8.5 | M5 × 8 | 5 | 4.5 | 14.5 | 1,200 | 0.025 | 0.45 |
| GH30QK | 1260003 | 90 | 28 | 42 | 6 | 45 | 42 | 22 | 22 | 8.5 | M8 × 10 | 6 | 4.5 | 14.5 | 1,750 | 0.034 | 0.69 |
| GH35QK | 1260004 | 100 | 34 | 48 | 7.5 | 55 | 42 | 24 | 24 | 9 | M8 × 10 | 6.5 | 4.5 | 14.5 | 2,000 | 0.043 | 0.86 |
| GH45QK | 1260005 | 120 | 45 | 60 | 10 | 70 | 49 | 26 | 26 | 11.5 | M10 × 15 | 13 | 4.5 | 14.5 | 2,350 | 0.049 | 1.51 |
| All product data (pictures, dimensions, tables, drawings) are provided as received from the supplier; we exclude liability for their accuracy or completeness. | |||||||||||||||||
QK operating pressure: 0.55–0.80 MPa.
Dimension note: H represents the combined height of the clamp and a GHW-type flanged carriage. H2 represents the combined height of the clamp and a GHH-type square carriage with the required spacer blocks, where specified by the supplier.
QB Series – Normally Closed Dimensions and Technical Data
The reserved drawing position and the table below apply to the QB Series. Dimensions, holding-force values and net weights are taken from the supplied QB table.
| Model No. | SKU | W | WR | H | H1 | H2 | L | L1 | B | C | C1 | M × L1 | E | D1 | D2 | Holding Force (N) | Air Consumption (L/cycle) | Weight (kg) |
| GH20QB | 1260011 | 66 | 20 | 30 | 4.5 | – | 39 | 22 | 20 | 20 | 9.5 | M5 × 6 | 5 | 4.5 | 14.5 | 600 | 0.018 | 0.3 |
| GH25QB | 1260012 | 75 | 23 | 36 | 5.5 | 40 | 39 | 22 | 20 | 20 | 8.5 | M6 × 8 | 5 | 4.5 | 14.5 | 750 | 0.020 | 0.5 |
| GH30QB | 1260013 | 90 | 28 | 42 | 6 | 45 | 42 | 27.5 | 22 | 22 | 8.5 | M8 × 10 | 6 | 4.5 | 14.5 | 1,050 | 0.036 | 0.8 |
| GH35QB | 1260014 | 100 | 34 | 48 | 7.5 | 55 | 42 | 27.5 | 24 | 24 | 9 | M8 × 10 | 6.5 | 4.5 | 14.5 | 1,200 | 0.044 | 1.2 |
| GH45QB | 1260015 | 120 | 45 | 60 | 10 | 70 | 49 | 32 | 26 | 26 | 11.5 | M10 × 15 | 13 | 4.5 | 14.5 | 1,500 | 0.062 | 2.1 |
| All product data (pictures, dimensions, tables, drawings) are provided as received from the supplier; we exclude liability for their accuracy or completeness. | ||||||||||||||||||
Normally Open and Normally Closed Comparison
Select the operating principle according to the required state when pneumatic pressure is absent.
| Characteristic | QK Series – Normally Open | QB Series – Normally Closed |
|---|---|---|
| State without compressed air | Released | Clamped by spring force |
| Function of compressed air | Applies the clamping force | Releases the clamp for movement |
| Behaviour after loss of air pressure | The rail is released | The clamp engages or remains engaged |
| Typical selection reason | Controlled stationary holding where air is continuously available | Pressure-loss holding, including suitably designed vertical-axis applications |
| Dynamic stopping | Not specified by the available supplier data | Not specified by the available supplier data |
Working Principle
QK Series – normally open: compressed air moves the actuator and internal force-amplifying wedge mechanism. The contact elements press against the free rail surfaces and generate the specified holding force. Removing air pressure retracts the mechanism and releases the rail.
QB Series – normally closed: an internal spring mechanism applies the clamping force when pneumatic pressure is absent. Supplying compressed air counteracts the spring force and opens the clamp so the guided axis can move. Removing pressure returns the clamp to its holding state.
Because the clamp acts directly on the profile rail, the stationary holding load does not have to pass only through the screw drive, belt, rack, coupling, gearbox or motor brake. This can improve local axis rigidity and reduce static loading of the drive train.
Selection, Compatibility and Applications
Match the clamp to the exact rail manufacturer, rail profile, nominal size, carriage arrangement, installation height and available clamping surfaces. A matching nominal size alone does not prove compatibility. The corresponding SHAC profile-rail references are GHR20, GHR25 and GHR30 for the selectable 20, 25 and 30 mm variants.
| Clamp Model | SKU | Series | SHAC Rail | Nominal Size |
|---|---|---|---|---|
| GH20QK | 1260001 | Normally open | GHR20 | 20 mm |
| GH20QB | 1260011 | Normally closed | GHR20 | 20 mm |
| GH25QK | 1260002 | Normally open | GHR25 | 25 mm |
| GH25QB | 1260012 | Normally closed | GHR25 | 25 mm |
| GH30QK | 1260003 | Normally open | GHR30 | 30 mm |
| GH30QB | 1260013 | Normally closed | GHR30 | 30 mm |
Typical applications include CNC machine axes, machining and positioning tables, tailstocks, fixtures, cutting and slitting equipment, robotic mechanisms, handling systems, packaging machinery and automated production equipment. Apply the clamp after the axis reaches a controlled stop unless the supplier separately confirms permissible dynamic braking energy and stopping duty.
Installation and Safety Essentials
- Verify the rail profile: confirm rail width, height, side geometry, free clamping surfaces, mounting pattern and clamp clearance.
- Calculate the required holding force: include axis mass, orientation, external process forces and the required safety factor.
- Use clean, regulated compressed air: follow the supplier pressure specification and use secure, leak-free pneumatic connections.
- Confirm release before motion: the control sequence should verify that the clamp is fully open before commanding axis travel.
- Protect the contact surfaces: contamination, corrosion, unsuitable coatings or excess lubricant can reduce obtainable holding force.
- Use static holding unless otherwise rated: do not assume the clamp is suitable for emergency stopping or repeated dynamic braking.
⚠️ Safety note: the normally closed QB principle improves pressure-loss behaviour, but the complete safety function still depends on verified holding force, pneumatic circuit design, valve response, installation orientation, control architecture and risk assessment. Do not treat the clamp alone as a certified safety brake unless the manufacturer documentation explicitly provides that rating.
Product Videos
The videos below demonstrate pneumatic clamping and braking elements used with profile linear guide rails.
FAQ frequently asked questions
What is the main difference between the QK and QB Series?
The QK Series requires compressed air to clamp. The QB Series uses spring force to clamp and compressed air to release.
Which series is preferred when loss of air pressure must not release the axis?
The normally closed QB Series is the appropriate operating principle, provided the selected model has sufficient holding force and the complete machine safety function is validated.
Can these clamps stop a moving axis?
Use them primarily for static holding after a controlled stop. The available data specifies holding force but does not specify permissible braking energy or repeated dynamic stopping duty.
Does the clamp replace the linear-guide carriage?
No. It provides clamping only and does not replace the carriage’s guiding and load-carrying functions.
Why clamp directly on the rail?
Direct rail clamping holds the moving structure without routing the complete static holding load through the screw, belt, rack, coupling or motor brake.
How is the correct model selected?
Match the exact rail profile and nominal size, then verify installation height, spacer requirements, mounting dimensions, holding force and available space.
