High-Torque pan/tilt kit

Hallo,
I have an object that weights about 4 kg which i would like to pan/tilt.
The problem is, that the standard pan/tilt kits one can buy in various shops are too weak to handle the object...
Does anyone know about a good way to pan/tilt heavy objects?

First calculate the torques you'll need - add a generous factor to ensure reliable operation then
you'll have three routes I think - large commercial servo units, large size stepper motors or
geared DC motors with encoders.

It will help to try and get the mechanics designed so the rotation axes running through the centre
of mass of the platform and its payload. Then the torques are minimized (but remember there
is bearing resistance that depends on the total mass however well balanced it is).

Fairly small servos can be used to pan/tilt fairly heavy loads as long as the loads are balanced where the servo does not have to supply a holding force. servocity below has some pan/tilt equipment.

http://www.servocity.com/html/mpt1100-ss_pan___tilt_system.html
http://www.servocity.com/html/spg400a-45_servo_gearbox.html