AshtonTucker Drive Units

Drive units from AshtonTucker are rated by the amount of torque they can produce on a continual basis for 20 years.  This differs substantially from Duty Rated Torque used by many manufacturers over the years.  (For an overview discussing Duty Rated Torque, please see http://www.ashtuck.com/blog/oil.php )  For instance, a drive that is Duty Rated for 10,000 ft-lbf will trigger a torque alarm at 30% or 3,000 ft-lbf.   Above this point, the operators are acknowledging that drive life is being diminished.  Often times, the 30% alarm level is actually the torque level where the drive is rated to last 10 years.  So a drive Duty Rated for 10,000 ft-lbf, would be somewhat comparable to a continuous rated drive at 3,000 ft-lbf.  Please keep this information in mind when comparing drive units.

Direct Drive – Example Model Number 10227

This drive unit supplies the torque for the clarifier or thickener, but does not offer any overturning moment capacity for unbalanced loads such as a skimmer going over a scum box.  These forces are generally assumed to be small where this drive is applied due to the use of underwater bearings or guides, or by the nature of small size of the mechanism used.

The rated torque capacity is a function of the output speed.  The faster the speed, the shorter the life, or the lower the torque rating.  While virtually any output speed can be achieved, standard speeds and torques are as shown in the table.

RPM Torque [ft-lbf] Torque [Nm]       0.08 3700 5050   0.17 3430 4650   0.22 3300 4500   0.3 3225 4375   0.34 3175 4300   0.38 3125 4250   PEAK 5150 7000

G19 – Example Model Number 10225

This drive uses a precision bearing to take overturning moments up to 40,000 ft-lbf that allows for unforeseen and unbalanced loading of the drive unit.  The torque capacity of this drive is a nominal 6,800 ft-lbf continuous for 20 year.  The rated torque is a function of the output speed as shown in the standard speeds table.  Again, virtually any speed can be achieved, with a corresponding rated output torque at that speed.

RPM Torque [ft-lbf] Torque [Nm]     0.08 6800 9250   0.09 6750 9150   0.1 6600 9000   0.12 6500 8850   0.13 6450 8750   0.14 6400 8650   PEAK 10600 14500

G19M – Example Model Number 10237

This drive unit is the big brother to the G19.  The nominal rated torque is 10,000 ft-lbf.   The attachment of the thickener or clarifier shaft differs at this higher torque capacity.  The rated torque table is as shown below.

RPM Torque [ft-lbf] Torque [Nm]     0.06 10650 14450   0.07 10600 14350   0.08 10400 14100   0.09 10225 13850   0.1 10150 13750   0.11 10000 13600   PEAK 12900 17500

Cage Drive Unit – Example Model Number 10226

This is a column mounted drive unit, for use with a center cage system to transmit torque to the mechanism.  The precision bearing used allows for an overturning moment of 300,000 ft-lbf making it suitable for clarifiers up to 100 feet in diameter.  The nominal toque rating for this drive is 30,000 ft-lbf continuous for 20 years.  Like all the other drives mentioned, virtually any output speed can be achieved, however standard speeds and rated torque are as shown in the table below.

RPM Torque [ft-lbf] Torque [Nm] 0.028 35500 48100 0.032 35300 47800 0.038 34600 46900 0.041 34300 46500 0.046 33700 45600 0.061 32600 44200 0.089 30750 41600 PEAK 46500 63000