---
title: "Is the ZA-I self-locking and when is a motor brake required?"
url: "https://zimm.com/wiki/is-the-za-i-self-locking-and-when-is-a-motor-brake-required/"
datePublished: "2026-10-13T05:49:00+00:00"
dateModified: "2026-10-14T06:50:16+00:00"
author: Jonathan Mildner
lang: en
canonical: "https://zimm.com/wiki/is-the-za-i-self-locking-and-when-is-a-motor-brake-required/"
markdown: "https://zimm.com/ai/wiki/is-the-za-i-self-locking-and-when-is-a-motor-brake-required.md"
categories: "Questions and answers about our products, Electromechanical actuators"
---

The ZIMM ZA-I is available with a trapezoidal screw or ball screw drive. Whether a load can be held without motor torque depends on the specific screw version and the selected holding concept.

### What applies to ball screw drives?

A ball screw drive operates with rolling friction and is not self-locking. A motor brake is therefore required for a ZA-I with KGT. This applies to the DA, P1 and P2 drive variants.

### What applies to trapezoidal screws?

Trapezoidal screws operate with sliding friction. Self-locking can occur at small lead angles. The specific screw version must be considered for this. A motor brake is required for two-start screws.

### What additional function does a motor brake perform?

A motor brake is also recommended to reduce overrun. The required braking torque depends on the load case and the drive. Particularly with a vertical installation position, the load, movement sequence and braking concept must be coordinated. The load-holding behaviour must therefore be assessed on the basis of the selected screw version and the requirements for load support.