The LK series linear units are designed to convert the torque output from an electric open/close or modulating actuator (CM series) into an axial force, primarily for use with valves requiring linear positioning movement. This conversion is achieved through a ball screw drive mechanism, which offers enhanced control accuracy and extended operational lifespan compared to other drive types. The specific combination of actuator and linear unit is determined by the required thrust and stroke length for the application.

Function Description:

The core function of the LK linear unit is to translate rotational motion from an actuator into precise linear motion. This is crucial for controlling valves that operate by moving a stem linearly to open or close, or to modulate flow. The ball screw drive is a key component, ensuring efficient and accurate force transmission. The linear unit itself comprises a robust cast housing, a mounted spindle nut, and a non-rotating spindle. To maintain operational integrity and prevent contamination from dusty ambient air, the unit is fully sealed with O-rings at the output.

Important Technical Specifications:

The LK linear units are available in several variants, each with specific technical data:

LK50:
- Actuator: CM03
- Output flange: G0/F10
- Stroke: 50mm
- Output thread: M20x1.5
- Pitch: 5mm/rev
- Factor (Nm/kN): 1.06
- Weight: 12.3 kg
LK100:
- Actuator: CM03
- Output flange: G0/F10
- Stroke: 100mm
- Output thread: M20x1.5
- Pitch: 5mm/rev
- Factor (Nm/kN): 1.06
- Weight: 15.0 kg
LK120 (two variants):
- Variant 1:
  - Actuator: CM06
  - Output flange: G0/F10
  - Stroke: 120mm
  - Output thread: M20x1.5
  - Pitch: 5mm/rev
  - Factor (Nm/kN): 1.06
  - Weight: 19.2 kg
- Variant 2:
  - Actuator: CM06
  - Output flange: G/F14
  - Stroke: 120mm
  - Output thread: M36x3.0
  - Pitch: 5mm/rev
  - Factor (Nm/kN): 1.06
  - Weight: 23.6 kg

The internal components of the linear unit include an output flange, various O-rings for sealing, a groove nut, bearing plate, axial deep groove ball bearing, bearing ring, intermediate flange, housing tube, base flange, wiper, feather keys, ball screw spindle, coupling and output shaft, cup spring, spindle pin, and spindle pin ring nut.

Usage Features:

The assembly and disassembly of LK linear units on valves require adherence to specific safety and operational guidelines:

Qualified Personnel: Only qualified personnel familiar with the product's assembly, commissioning, and operation should mount and commission the device.
Depressurization: Before assembly or disassembly, the pipes where the valve is installed must be depressurized. Removing the actuator from the linear unit will cause the valve stem position to be unfixed due to the linear unit's non-self-locking property.
End Stops: The linear unit has mechanical end stops. It is critical not to move against these end stops during electrical operation to prevent damage. Actuator end limits must be set accordingly.
Valve Cone Position: The valve cone should never be brought into the CLOSED position with excessive force, as this can damage high-quality sealing edges.
Assembly Procedure:
1. Verify matching flanges between the actuator, linear unit, and valve.
2. Thoroughly clean all screw-on surfaces and bare parts.
3. Lightly grease connections and the linear unit spindle.
4. Move the valve cone to the CLOSED position.
5. Turn the spindle nut to place the linear unit in a central position.
6. Mount the linear unit on the valve, tightening screws crosswise. The coupling will be connected later.
7. Mount the actuator on the linear unit, tightening screws crosswise.
8. Extend the spindle using the handwheel until the coupling of the linear unit and the valve align.
9. Connect the coupling.
10. Use the handwheel to move the linear unit to a center position to prevent damage during startup.
Disassembly Procedure:
1. If the valve is fully closed, move the valve cone to approximately ten percent OPEN.
2. Loosen screws between the actuator output flange and the linear unit, then dismount the actuator.
3. Open the spindle coupling between the linear unit and the valve.
4. Loosen screws between the linear unit output flange and the valve.
5. Dismount the linear unit from the valve.

Maintenance Features:

Regular maintenance is essential to ensure the longevity and optimal performance of the LK linear units:

Running Noises: Pay attention to increased running noises. If observed, grease the two lubrication nipples of the linear unit to lubricate the bearings and spindle guidance.
Fixing Screws: Regularly check the fixing screws between the actuator, linear unit, and valve for firm hold. Tighten them to the specified torques if necessary, as detailed in the "Installation instructions" chapter of the standard user manual.
Moving Interval: The linear unit should be actuated at least every 3 months to prevent seizing and ensure smooth operation.
Greasing Interval: Every 6 months, the linear unit should be re-greased via the greasing nipples.
Lubricant Recommendation:
- Type: Lubricating grease DIN 51825-K(P) R -40. This is a water-repellent complex grease based on Al-soap, offering high resistance to acids and alkalis.
- Ambient Temperature Range: -40 to +85 °C
- Worked Penetration (0.1 mm): 310 - 340
- Dripping Point: Approximately 260 °C
- NLGI-Class: 1
- Properties: Acid-free, not or only slightly reactive with water.

SCHIEBEL LK Series - Page 2

Table of Contents