Lightweight monorail track and dolly design

The Mumford Monorail is an exceptionally efficient, compact, and light weight motorizedf track and dolly. We have refined a design that's ideally suited for remote locations where the gear has to be carried in. It's much smaller and lighter than "skateboard wheel" designs. A four foot track and carriage weigh less than seven pounds. The Time Machine, motor driver, and battery all fit in a small Pelican 1200 case.

The Moco Time Machine can drive the carriage in equal increments between each exposure, or with ramped pan programs. Our new stepper motor driver can also run the dolly in continuous motion over a variable range of speeds with a built-in pulse generator.

Because the carriage is driven with a stepper motor, it moves a precise amount between each exposure. You can rewind a sequence back to the beginning and rely on the Time Machine to execute an identical movement each time.


We have found that the standard bearing pads made for the aluminum rail have too much play for a perfect fit. This will cause the carriage to rock or tilt a tiny amount, resulting in a visible jog in the final time lapse.

We correct this by machining custom bearing pads out of Delrin that fit the monorail precisely. Additionally, our bearing pads run the full length of the carriage, which insures better alignment, smoother action, and longer life.



We have added a screw adjustment to each side of the carriage to take up any remaining horizontal play.

Four more Nylon adjusters on the top of the carriage take out any vertical play. These features produce a sliding carriage that's a perfect machined fit to the rail with no wobble or play.

Initial assembly takes about ten minutes to attach the two end plates, mount the motor, run the toothed belt around the pulleys, and secure it in the clamps. After that it can be transported fully assembled. Tapped holes in the bottom for 1/4-20 or 3/8-16 threads allow you to attach your tripods at each end.

Six foot monorail with a ball head on the carriage



Click here to see a short movie of the light weight monorail track and dolly in action.

The toothed belt and pulley will easily raise the camera up a fully vertical incline.


Click here to see a time lapse sequence illustrating the positioning accuracy of the monorail dolly and stepper motor. A stepper motor allows greater accuracy of position than a DC motor because each increment of movement is a fixed increment of motor rotation. If you ask the camera to move 1,000 steps, it moves exactly this amount each time. If you need to accurately plan the ending position of a shot, shoot an identical sequence a second or third time, or have precise increments in a stop action sequence, this is important.

In this clip the Time Machine was set to advance 1/2" between each exposure. It may be a little confusing because it looks like the tape is moving. But the tape is stationary and the camera is mounted to the carriage that moves down the track over the tape.




Click here to see a short sample of a ramped move on the monorail dolly.






You can also mount the Miniature Rotary Table on top of the monorail and drive them simultaneously with the Moco Time Machine. This allows you to track a subject in the middle of the frame as you move down the track.
Click here for a example of such a movement.




The Monorail motor is perfectly strong enough to raise a camera and a Miniature Rotary Table up an incline. This movie shows such a climb in continuous motion made possible by the jog function of the Mumford Motor Driver. Stepped "shoot-and-go" operation with the Moco Time Machine is also possible.




Click here to see a short linear move filmed on the monorail by Chris Dortch in Bethelhem.