Abstract: Energy is stored in a hoop 12 spinning around a stator 10 both made of soft steel. At the interface between them there is a cavity in which there are conductors to provide a magnetic bearing between the hoop and the stator. A magnetic levitation device keep the hoop levitated. Energy is imparted to and withdrawn from the hoop by means of linear reluctance motors.

Abstract: A slack rope detecting apparatus for use in mine winding operations provides a trip signal via contacts 34 if the load in the rope falls below a predetermined value. The apparatus senses the load at each side of a sheave wheel using transducers 6 and 8 and uses a mean value of their outputs as an input to a summation amplifier 12. The weight of the rope between the sheave wheel is compensated for by monitoring rotation of the winding engine drum 42 and providing corresponding input signals for the amplifier 12. When the effective load in the rope falls below a predetermined value, set by input 28, a trip signal is produced. The trip signal output is preferably visually displayed and recorded.

Abstract: A single chamber ionization-type fire detector. The ionization current is directly amplified to provide a usable analogue signal by means of an operational amplifier which has a minimal effect in the ionization current. The operational amplifier is simultaneously employed to maintain a constant potential difference in the chamber so that the ionization current is not subjected to a fluctuating voltage. The amplified analogue signal drives a recorder and through analysis of the recorder output genuine fire alarm conditions can be distinguished from false alarm conditions.