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Peanut Digger Conveyor Speed Calculator

Some diggers now incorporate in-cab conveyor speed readouts, which show the conveyor speed so it can be adjusted according to the desired speed. In the absence of such digital readouts, this online calculator provides operators with a tool to measure conveyor speed with a stopwatch.

Our tests have shown optimum conveyor speed in "not rank" vine conditions to be roughly matched to the ground speed. These tests also showed optimum conveyor speed in "rank" vine conditions to be as low as 70-85% of ground speed. These results were from tests where the inversion rods were set to manufacturers' recommendations. Both Amadas and KMC diggers were tested, with similar results.

Scroll down for full explanation and instructions, or use our printable Peanut Conveyor Speed Cheat Sheet.


(Optional stopwatch provided below.)

Conveyor speed:

Conveyor speed:

The (optional) stopwatch timer provided above is from an external source. It allows for multiple readings and outputs the average if multiple checks are desired.
Note: In some browsers the "start in" value defaults to 10 sec, despite displaying 0 sec. To resolve, click "start in" dropdown and click "0 sec".

Explanation: Clemson tests have shown that proper conveyor speed can be critical to minimizing digging losses and maximizing yield. Generally, our tests have shown that matching the conveyor speed to the ground (travel) speed is best for normal (not rank) vine conditions. However, in rank vines (excessive vine growth) we have shown optimum conveyor speeds to be lower than forward travel speed. We believe that this is the case because when the vine load is heavy, a "choke point" occurs at row convergence, just after leaving the conveyor but prior to inversion. We have observed this "choke point" to reduce the velocity of the vines. When the velocity of the vines slows between the end of the conveyor and inversion, but the velocity of the star wheels does not slow, a difference in velocity occurs between the vines and star wheels. We believe that this difference in velocity is often responsible for a great deal of observed above ground losses, where the pods are being sloughed off by the star wheels. The solution is to reduce the "choke point" effect, which can be accomplished by either (1) slightly opening the upper two or three pairs of inversion rods on the back of the digger or (2) slowing the conveyor speed and therefore the star wheel speed...or some combination of the two.

Procedure for using this calculator: Place a flag of masking tape on the middle of one conveyor bar. With the tractor in park at normal operating pto speed, check to make sure all is clear at moving parts of digger digger and engage the hydraulics (or pto) to run the conveyor. Pick a stationary visual reference on the digger for the flag of masking tape; rolling over the top of the conveyor may be convenient. Start a stopwatch when the flag of tape passes your visual reference point and stop the stopwatch once the conveyor (flag of tape) makes 10 full revolutions. Input the time (in seconds) it takes for 10 revolutions of the conveyor; this calculator will output your conveyor speed in mph. It may be worthwhile to complete the test several times and average the results, especially at higher conveyor speeds. Optionally, input your intended ground speed and conveyor speed as a percent of ground speed will also be calculated.

Note: This calculator is based on Amadas diggers with 29 conveyor bars and 5.94 in. average bar spacing or KMC diggers with 20 conveyor bars and 6.58 in. average bar spacing. If your conveyor is different from these, then the calculations provided here will not be correct for your digger; please let us know and we can add calculations here that match your digger's measurements.

Rather have a printout?
Click the following link for our printable Peanut Conveyor Speed Cheat Sheet (pdf format).

APA Citation:
Kirk, K.R., Fogle, B.B., Thomas, J.S., Anco, D.J., Warner, A.C., Massey, H.F., and McAlhany, F. (2018). Peanut Digger Conveyor Speed Calculator. Clemson University Precision Agriculture. Retrieved from

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