Speedo Cable Drives

Speedometer drive

The rotation of the wheel (front, rear or in the gearbox) is translated and redirected via an angle drive or worm gear. The flexible speedometer cable then transmits the rotation to the speedometer itself. Within the speedometer, the rotation of the shaft is then converted into the deflection of the pointer.

What mechanical speedometer drives are there?

Depending on the installation location, they are divided into rear wheel connection, gear connection and front wheel connection. The drives for the good old Corbin accessory tachometers were bolted to the frame. The wheel rotation was taken off via a ring gear and a Bakelite gear. For the connection to the speedometer shaft, there are different threads according to diameter and pitch. The counterpart on the speedometer cable in the form of a connecting nut must be compatible.

It is also important that the drive ratio matches.

There are many different gear ratios available for speedo drive units. For transmission-mounted drives, make sure the small gear on the drive meshes properly with the large gear on the mainshaft—otherwise you'll end up with a mess of chewed-up teeth. With speedo drives that mount on the wheel axle (so-called “speedo worms”), the gear ratio is fixed inside the unit. That’s why we always list it in our shop. The ratio tells you how many times the speedo cable spins for each full rotation of the wheel. For example, a 1:3.75 ratio means the cable spins 3¾ times per full wheel revolution.