Intermediate positions for swivel units Tips and tricks

ZWP Module: How to achieve intermediate positions with swivel units

A swivel drive can do more than just 0° or 180°. But how do you precisely stop a swivel unit in the middle, for example, to unload a rejected part?
Many designers don't know that there's a simple solution for this: The ZWP module. In this guide, we'll summarize everything you need to know about intermediate positions, damping, and torques.

1. The Function: What is a ZWP Module?

The ZWP module (intermediate position) is an additional module for the SE and SES series swivel units. It allows for a third position to be reached within the swivel range. Intermediate positions for our swivel units are available per module size.

The key point: You don't have to use expensive electrical solutions if a firmly defined intermediate position around the center is sufficient.
Flexibility: The position is freely adjustable within the total stroke around the center position by +/-20° (for ZWP-9-SES by +/- 10°).
Accuracy: Despite direct action on the rack, the accuracy of the ZWP is 0.05°.

2. Damping: Why it's worth considering here!

Shock absorbers are usually installed at the end positions. But what happens in the middle? Does the mid-position in the relevant application require damping?

In the intermediate position, the coupled additional ZWP module inserts two piston rods into the pressure chamber of the swivel unit. This pushes their racks into a "middle position".
Damping may not be necessary in the mid-position, depending on the application.

💡What you should pay attention to:

The ZWP module should always be combined with a shock-absorbing component (hydraulic shock absorbers) if you are approaching the mid-position at high speed and/or with a workpiece. An example here would be the unloading of a "n.i.O. workpiece" (not in order workpiece).
If the mid-position is used to pick up the workpiece (for example, to initiate a positionally correct unloading later by camera), the approach to the middle occurs without mass. In this case, a shock absorber can be omitted.

💡Expert Tip:

We recommend the use of dampers for high moments of inertia, or at least the use of throttles to avoid hard stops.

3. Effective Torques: Physics cannot be tricked

An often overlooked point is the effective torque in the intermediate position.
Since the ZWP module, as an additional cylinder, mechanically moves back (or locks) the racks of the swivel unit, it interferes with the movement sequence! The available space results in a maximum possible piston diameter per installation space. Depending on its size, the intermediate positions can sometimes be engaged even against the pressurized racks of the swivel unit. However, this reduces the effective torque. In this respect, depending on the application and use (necessary torque), the swivel unit must be vented beforehand (pressureless).

	Torque	Torque	Torque
	SE \| SES	ZWP	ZWP
Module Size	@6bar effective	vs. SE \| SES @6bar	SE \| SES pressureless
SE-4	0.94 Nm	not possible	0.9 Nm
SES-4	1.6 Nm	1 Nm	3 Nm
SE-6	3.5 Nm	not possible	3.5 Nm
SES-6	6.5 Nm	1.9 Nm	10.1 Nm
SE-9	12 Nm	5 Nm	20.2 Nm
SES-9	24 Nm	8 Nm	40 Nm

The intermediate positions for SE-4 and SE-6 can only be operated (due to design) with the swivel unit pressureless!

🎥 Moving images of the inner workings of an intermediate position:

💡Expert Tip: Control of Intermediate Positions on Swivel Units

As mentioned: An additional module is coupled directly to the swivel unit and inserts two piston rods into the pressure chamber. This pushes the racks of the swivel unit into a "middle position". Two cylinders thus act against each other.

Download: Here you will find our tips on control and throttling as a PDF file or interactively as a PowerPoint:

PowerPoint: "Tips on ZWP"

PDF: "Tips on ZWP"

💡For design: 3D data of examples

Exemplary STP files or CAD data of swivel units with mounted intermediate positions (without damping) can be found here:

Swivel Unit	Intermediate Position	3D Model	Note
SE-4-N-190-K-0-0-P	ZWP-4-SE-20-K-0-0-P	CAD File	Without damping
SE-4-N-190-H-2-0-P	ZWP-4-SE-20-K-0-0-P	CAD File	With damping
SES-4-S-190-K-0-0-P	ZWP-4-SES-20-K-0-0-P	CAD File	Without damping
SES-4-S-190-H-0-0-P	ZWP-4-SES-20-K-0-0-P	CAD File	With damping
SES-4-S-190-K-4-0-P	ZWP-4-SES-20-K-0-0-P	CAD File	Without damping

Conclusion: Why the ZWP Module is your best friend!

Instead of complicated special designs, the ZWP module offers a modular, robust, and cost-effective way to extend the functionality of your swivel unit with a third position. If you consider damping and effective torques, it's an "install and forget" solution.

💡 ZWP intermediate positions are additional modules and can also be attached later if required!

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