Apparatus at a spinning preparation machine for the purpose of monitoring

In an apparatus at a spinning preparation machine, especially a flat card, roller card or the like, for the purpose of monitoring, a clothed, rapidly rotating roller lies opposite to at least one clothed and/or non-clothed component, and the spacing a between the components lying opposite to one another is changeable. To avoid contact between the components lying opposite to one another in a simple manner, in order to monitor the spacing, there is located opposite to the clothing of the roller, spaced therefrom, a sensor that is arranged to respond in the event of contact between clothing and sensor.