Grob linear drives provide for the right profile on the stages of the world's theatres

1. Grob GmbH Antriebstechnik –
74889 Sinsheim
www.grob-antriebstechnik.de
Tel. +49 7261/92630
1 | P a g e
Grob linear drives provide for the right profile on the
stages of the world's theatres
Anyone who has ever been to
the theatre knows that the
scenery is changed or
rearranged during the
intermissions. When you
return after the intermission
there's a different stage
setting. It's much the same in
film studios.
What has happened?
Depending on the theatre stage,
the entire stage is revolved or
parts of the stage are changed
by a different stage profile. But how does that work in detail and why does the
conversion take place so quickly?
The solution is simple: a complete lifting
system is accommodated below the stage.
There can easily be 100 or more linear
drives under a theatre stage.
Why so many linear drives? The stage
platform is expected to be highly rigid and
this is achieved through the large number
of linear drives. Not only that, the stage
profile can be changed and adapted with
great variation thanks to the large number
of linear drives.
The task of the linear drives: they lift or lower parts of the stage. The stage can thus
be changed during the performance or during the intermission.
Stage setting. Image rights: pixabay
Lifting system. Image rights: Grob GmbH Antriebstechnik

2. Grob GmbH Antriebstechnik –
74889 Sinsheim
www.grob-antriebstechnik.de
Tel. +49 7261/92630
2 | P a g e
The structure of complete lifting systems
The force generated by the electric motor is transmitted via Cardan shafts to the
transfer gearbox, which diverts the torque from the drive to the spindle or to the linear
drive. The diversion in the transfer gearbox is done by bevel gears. Transfer
gearboxes can thus synchronise "any" number of linear drives that are not arranged
in the same axis.
The Cardan shafts transmit the torques both positively and non-positively between
the individual linear drives, the bevel gearboxes and the drive motor. In addition, they
synchronise the linear drives. The individual lifting legs can, of course, also be
electronically controlled via rotary encoders and set at different heights.
The challenge: to make the lifting system as efficient as
possible
When it comes to building the lifting system, there's not much to it. The challenge is
much more one of designing the lifting system so that the required torque also
reaches the last linear drive in the system. And to optimise the control so that the
stage setting can be changed with such great variation.
Complete lifting system with four linear drives, two transfer gearboxes
and four Cardan shafts: image rights: Grob GmbH Antriebstechnik

3. Grob GmbH Antriebstechnik –
74889 Sinsheim
www.grob-antriebstechnik.de
Tel. +49 7261/92630
2 | P a g e
The structure of complete lifting systems
The force generated by the electric motor is transmitted via Cardan shafts to the
transfer gearbox, which diverts the torque from the drive to the spindle or to the linear
drive. The diversion in the transfer gearbox is done by bevel gears. Transfer
gearboxes can thus synchronise "any" number of linear drives that are not arranged
in the same axis.
The Cardan shafts transmit the torques both positively and non-positively between
the individual linear drives, the bevel gearboxes and the drive motor. In addition, they
synchronise the linear drives. The individual lifting legs can, of course, also be
electronically controlled via rotary encoders and set at different heights.
The challenge: to make the lifting system as efficient as
possible
When it comes to building the lifting system, there's not much to it. The challenge is
much more one of designing the lifting system so that the required torque also
reaches the last linear drive in the system. And to optimise the control so that the
stage setting can be changed with such great variation.
Complete lifting system with four linear drives, two transfer gearboxes
and four Cardan shafts: image rights: Grob GmbH Antriebstechnik