Abstract: This invention describes a control mechanism for an electric main drive of a printing machine, whereby the electric main drive operates with a motor, a brake and a tachometer generator. The machine control of the control mechanism is connected to a multiplicity of signal transmitters (pushbuttons). The signal transmitters detect the machine state to ensure that the printing machine does not run at an excessively high speed. For this purpose, the invention outlines, in addition to the machine control, a monitoring device which detects the switching states of the signal transmitters, forms a highest possible permitted speed therefrom and compares this value with the actual speed value delivered by the tachometer generator. The electric main drive is shut down as soon as the actual speed value overshoots this upper limit.

Abstract: This invention describes a monitoring device which monitors the safety of a printing machine. The printing machine has a drive, a control unit arranged upstream of the drive, command buttons which are connected to the control unit and via which the start-up of the printing machine can be initiated, as well as sound generators, connected to the control unit, for the emission of an acoustic alarm signal after the actuation of one of the command buttons initiating the start-up. The monitoring device ensures that a start-up of the printing machine is only carried out if an acoustic alarm signal has previously been properly emitted. This is achieved, according to the invention, by the monitoring device registering the emission of the acoustic alarm signal and, in the event of the alarm signal not being emitted, inhibits the drive of the printing machine from starting up.

Abstract: A description of a method and a device for monitoring the braking of a D.C. motor of a printing machine such as a sheet-fed offset printing machine is given. For safety purposes, in the case of an emergency stop an electrical braking should always be carried out with the maximum torque of the D.C. motor. For this purpose, the disclosed method provides that the actual value of the armature current is detected and compared to a maximum permissible value for the electrical braking. In the event of an impermissibly high deviation and, in particular, in the event of an undershoot of the armature current relative to the maximum permissible value, the power converter and motor are disconnected from the power supply and an electrically actuable brake is applied to the motor.