Hennig Power Protection is a dedicated division specializing in custom-engineered generator enclosures, fuel systems, and power infrastructure for mission-critical applications across data centers, healthcare, telecommunications, and industrial facilities.
CLAMPING DEVICES AND LINEAR BRAKES ACTING ON ROUND RODS
Hennig is the exclusive North American provider of SITEMA® Safety Solutions—a globally recognized line of clamping units and linear brakes that act on round rods. SITEMA (based in Germany) is the only company in the world specializing exclusively in this field of rod clamping and braking technology, a focus that has made them the international leader in safety catchers and clamp units. With SITEMA’s products, you can equip your machinery with devices that automatically secure loads during power loss, provide redundant safety for vertical axes, and deliver precise locking for positioning tasks. From preventing a press ram from free-falling to holding a robotic arm in exact position, SITEMA solutions cover a wide range of applications where uncontrolled movement is not an option. We have partnered with SITEMA since 1992, bringing decades of expertise to our customers in applying these safety devices effectively.
Key Features
Fail-Safe, Power-Off Clamping
Automatic spring-engaged, power-released locks secure loads during power or pressure loss.
Infinitely Variable Positioning
Secure clamping at any position along the rod, enabling precise and flexible positioning without fixed notches.
Pneumatic or Hydraulic Actuation
Easily integrates with existing pneumatic or hydraulic cylinder systems.
Bi-Directional Holding
Equal holding force in both tension and compression directions, ensuring stability in all directions.
High Clamp Force
Supports load capacities from several hundred pounds up to 80,000 lbf, ideal for a wide range of cylinder sizes and press applications.
Rugged Reliability
Heavy-duty, industrial-grade construction with proven safety performance and certified compliance (OSHA/DGUV); engineered and manufactured in the USA.
SITEMA safety solutions add an essential layer of protection and control to machinery—catching gravity-driven loads, locking moving axes on demand, and enabling safer, more controlled operation in manufacturing, automation, and material handling environments
SITEMA's SiForce Technology introduces a self-intensifying clamping mechanism that enhances safety and efficiency in press operations. Unlike traditional spring-actuated systems, SiForce utilizes the load's own force to increase clamping strength, ensuring that the clamp tightens as the load increases. This design offers several key benefits:
Key Features
Fail-Safe Operation
The clamp cannot be released under load, preventing unintentional disengagement and ensuring operator safety.
Pneumatic Capability
Capable of securing loads up to 220 kN using pneumatic actuation, eliminating the need for hydraulic systems in certain applications.
Compact Design
By eliminating large spring packs, SiForce clamping heads are more compact, allowing for easier integration into existing systems.
Long Service Life
Reduced wear on components leads to extended operational life and lower maintenance requirements.
Emergency Accessibility
In the event of a malfunction, the system allows for upward movement even when the clamp is engaged, facilitating the rescue of trapped personnel.
Power-Off Locking
Spring or mechanical wedge mechanisms automatically clamp the rod when power or pressure is lost, ensuring fail-safe load holding.
Certified Safety Compliance
Meets global safety standards including OSHA and DGUV approvals, giving you confidence in safe operation of vertical loads.
Automated and Resettable
Engages and disengages repeatedly, integrates with pneumatic or hydraulic systems, and easily resets for regular machine use.
Broad Application Range
Adapts to everything from small pneumatic cylinders to massive hydraulic presses, with options for static or dynamic load holding.
Industrial-Grade Reliability
High-strength steel, quality coatings, and proven performance over decades ensure durable performance in even the harshest conditions.
Press Safety and Clamping Devices
Product Lineup
Safety Catchers
Spring-actuated rod locks that instantly catch and hold falling vertical loads—ideal for presses, lifts, and more.
Safety Brakes
Pneumatically or hydraulically released brakes that secure vertical or inclined loads; perfect for dynamic axes like Z-axes.
Safety Locks
High-capacity static clamps for holding suspended loads; ideal for slow or stationary applications like lifts and cranes.
Locking Units
Dual-direction clamps that secure rods in both directions, offering precision holding and safety in varied conditions.
PowerStroke
Combines clamping with a short-stroke actuator for high-force press operations; ideal for molding, clinching, and forming.
Locking Unit for Torque
Clamps torque and axial forces with a single head, perfect for combined load holding. Series KFH, KFP, KB...
Rod Leaving the Clamping Head
Allows the rod to move completely out of the clamping unit; ideal for applications with space or accessibility constraints.
Mechanical Safety Catcher
Mechanical locking device for vertical loads, requiring no hydraulic or pneumatic system.
Electric-Pneumatic Module EPM
Interfaces between electrical control and a pneumatic SITEMA clamping head for versatile system integration.
Mechanical Valve Actuator MVA
Pneumatic clamping head actuator that secures chain rupture events with SITEMA reliability.
Auto Bleeder
Ensures the hydraulic system in a SITEMA clamp stays properly bled for reliable operation.
Why Hennig
Engineered for Your Industry
Press & Stamping
In press and stamping operations, you can never risk a dropped load or uncontrolled movement. When pressure fails or power is lost, Hennig's rod locks and press safety devices secure loads, hold positions and protect personnel.
Typical travel without the optional Spring Base is between 5 and 15 mm…with the spring base, an additional 6-10 mm depending on the size. Full travel with the spring base option can range between 10-25 mm depending on type and size. If the catcher does not bottom out/compress the Spring Base fully, then release pressure can be applied and unlock the catcher without an upward movement.
If the safety catcher is holding a load? You must first apply release pressure and then move the axis upward. At this time, you should be monitoring the “Unlocked” proximity switch indicating the status condition.
The typical reaction time of the SITEMA safety catcher is approximately 150 m/sec.
All mounting bracketry should be designed for 4 x M in the event of an overload condition.
No, the influence of mineral oil on the shaft is insignificant and you will not lose holding capacity.
Admissible Load (M) sizing is determined by the platen weight + tooling weight and anything mounted to the platen.
Factor of 100% is included. Minimum holding is 2 x M (admissible load) max holding is 3.5 x M. Force test required is 1.5 x M.
No, the clamp system requires approximately ½ inch of downward movement to develop full holding. The safety catcher’s are single acting and only hold against gravity.
* In case impact noises due to excess pressure are audible when pressurizing the safety catcher, these can be suppressed by means of a flow control valve in the p-line.
** In case the pressure is not sufficiently constant (e.g. pressure drop at the beginning of a downward stroke), we recommend a check valve in the p-connection of the valve.
PRESSURE FLUIDS To keep the clamping permanently open, safety catchers mostly are hydraulically actuated. Pneumatic versions are also available for smaller units.
Hydraulic Actuation:Hydraulic oil (HLP) in accordance with DIN 51524-2:2006 must be used as pressure fluid. Please consult SITEMA before using any other fluids.
Pneumatic Actuation:The compressed air must be dried and filtered. SITEMA recommends compressed air according to ISO 8573-1:2010 [7:4:4].
ACTUATION WITH A 3/2-WAY VALVE In most applications an actuation as suggested in Fig. 2 is used. During every operational cycle, the 3/2-way valve is actuated electrically and releases the safety catcher.
In all other operational conditions, as well as in cases of power-failure, pressure line breakage, emergency stop, etc. the safety catcher becomes effective, secures the rod and/or stops the load. If necessary the valve can also be switched by another safety signal, e.g. speeding, contouring error, etc.
MONITORING BY PROXIMITY SWITCHES Proximity switch 1 “load secured” signals the secure state and is used to authorize entrance to the danger zone.
Proximity switch 2 “clamping release” is used to activate the movement of the drive in the load direction.
For automatic detection of failures both signals are compared. In case both switches indicate the same state—apart from minor overlapping periods—there is a defect present.
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