A couple of months ago I upgraded my rally navigator’s tool box by adding a Halda Twinmaster fully mechanical odometer. This dual-display odometer is more versatile than the single display Halda Tripmaster that I already had. My newly acquired Halda Twinmaster is shown below.
My Halda Twinmaster
The well-known Halda Twinmaster and Tripmaster odometers came onto the market in the early 1960s. At that time the Halda Speedpilot had been available for about 8 years.
The central knob on the bottom front controls the direction that the odometers turns. When turned to the “+” sign, the values in the odometer increase, while when turned to the “-” sign the value of the odometer will decrease. When this knob is turned to the “O” sign, then the odometer is out of gear and the value will not change based on the direction of travel. This directional flexibility is useful when a rally car is off-course and trying to get back on course.
The bottom right knob controls the display that will be changed. Turning the knob to the left refers to the bottom display, the central position is for both displays, while turning the knob to the right changes the top display only in my Twinmaster.
The two knobs on the right side of the front face are for instantaneously zeroing each display. Pulling the upper knob will zero the top display and pulling the lower knob will zero the bottom display.
The common usage of the Halda Twinmaster is to use the upper display for the total distance traveled, while using the lower display to show the incremental distance traveled. That way the upper display can be used for timing purposes, while the lower display can be used for course following purposes. The knob on the right side of the Halda Twinmaster can be used to adjust the value shown in the upper display as described above.
Screws Provide Good Opportunities For Mounting
The Halda Twinmaster has some mounting screws build into the back of the unit to allow for easy mounting in a rally car. There is a small light for the odometer displays that is integral with the Halda Twinmaster, but it is not particularly bright. For night-time rallies I will use some auxiliary lighting.
My Halda Twinmaster is an old unit. This is indicated by the rather low serial number that is stamped onto the back of the Halda Twinmaster. The image below shows the serial number as “1547”.
Low Serial Number Indicates An Early Twinmaster
The newer Halda Twinmasters, especially the plastic-bodied Twinmasters also have the ability to adjust the lower display or set it to a particular value. Frankly I don’t see that as much of a functional difference, as the lower display is usually used for incremental distances. Therefore I had no qualms about purchasing an older unit. Mine works just fine. It is a good match with my Halda Speedpilots.
The Halda Twinmaster now gives me a good quality odometer that can be used in those rallies that penalize the use of electronic odometers and rally computers.
Now that I have a Halda Twinmaster, I no longer need my Halda Tripmaster, so if you know anyone looking for a Halda Tripmaster have them contact me – mine is for sale.
If you have any comments or questions about this post, then leave a comment below or send me a private email at the following address: shanna12 at comcast dot net