| Updated May, 2007 |  |
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File A3-26 |
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Matching Tractor Power and Implement Size
| Use this decision aid to match the size of a tractor to the size of an implement. |
For tillage and planting implements the size of the machine that can be used is often limited by the size of the available tractor. The horsepower needed to pull a certain implement depends on the width of the implement, the ground speed, draft requirement, and soil condition. The general formula for estimating the required horsepower measured at the power take-off (PTO) is:
PTO hp = width (feet) x speed (mph)
x draft (lb./ft.) x soil factor / 375
The soil factors are as follows:
Table 1 shows estimated draft requirements for various implements. For example, a 24-foot tandem disk being pulled at 6.0 mph in firm soil with a draft requirement of 200 pounds per foot of width would need the following PTO horsepower:
(24 ft. x 6.0 mph x 200 lb./ft. x 1.5) / 375
= 115 PTO hp
For some implements the width and the draft requirements are measured in terms of the number of teeth, shanks, or rows rather than feet.
