Drawbar Pull (Towing)
The towing capability of a tractor is defined in terms of drawbar pull;
quoted in Newtons (N). Two values of drawbar pull (DBP) need to be known;
maximum DBP for starting from rest and continuous or rated (rolling) DBP at
which the tractor can work for longer periods. Surface Resistance (SR) must
also be allowed for; a table is given below, in terms of Newtons per tonne
towed load. For average calculations, we use 400 N/tonne starting and 200
N/tonne rolling.
Tow Tractor Technical Data:
| DBP |
= |
Drawbar Pull (N) |
| WT |
= |
Weight of Tractor (tonnes) |
| WL |
= |
Weight of Towed Load (tonnes) |
| SR |
= |
Surface Resistance (N/tonne) |
| 98 |
= |
Conversion Factor |
| G |
= |
Gradient expressed as a % e.g. 12 1/2 % |
| On the level, DBP |
= |
(WL x SR) Newtons |
| On a gradient, DBP |
= |
(WL x SR) + ((WT x WL) x 98 x G) Newtons |