Bicycle Speedometer Adapted To High-Clearance Sprayer

Bicycle Speedometer Adapted To High-Clearance Sprayer SPRAYING Miscellaneous 28-3-33 When the speedometer on his high clearance crop sprayer failed, Merritt Wade, Lexington, Ky., saved money by replacing it with a bicycle speedometer. He mounted a series of magnets on one of the sprayer's undriven wheels. A bracket holds the speedometer's sensor close to the path where the magnets pass. The miles per hour - shown in tenths of a mile per hour - is displayed on a digital monitor on the operator's console. "A new replacement speedometer would've cost about $150, and a commercial radar-type, ground speed monitor $400 or more. I spent a total of only about $25," says Wade. "I got the idea one day when I was installing a digital speedometer on my son's bike and wondered if I could make it work on my sprayer. Normally there's a single, spoke-mounted magnet that passes a sensor with each wheel revolution. The digital readout displays the speed in increments from 1 to 99 mph." To fit the sprayer, Wade mounted five magnets, equally spaced around the wheel rim. He recalibrated the unit so it would read in tenths of miles per hour (i.e. 4.5, 8.3, etc.). He sanded off the paint on five equally spaced locations on the rim and then epoxied a magnet onto each location. He made a small bracket to hold the sensor close to the path where the magnets pass. Then he ran a wire up to the digital readout in the cab. He measured the rolling diameter of the sprayer tire and divided by five (the number of magnets). He then multiplied by the calibration factor given in the manual and divided by 10 to give tenths of miles per hour. "It lets me spray much more accurately than I used to and maintain a constant speed in all conditions, whether I'm going up hill or downhill or on dry or muddy ground," says Wade. "I bought the magnets at Radio Shack and the speedometer at Sears. "I've used this same type of bicycle speedometer on other implements. I made a unit for my vegetable planter where live plants are planted by hand. I have to plant vegetables at very slow speeds - 1.2 to 1.7 mph - and a steady speed is important for maximum productivity. The speedometer I use on the vegetable planter is calibrated to read in hundredths of miles per hour (i.e. 1.34 mph)." Contact: FARM SHOW Followup, Merritt Wade, 1651 Elkchester Road, Lexington, Ky. 40510 (ph 859 254-4512).

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