BigMike
Bronze Member
Guess us boys in the southwest forget that snow load stuff. Have to worry about wind loads here, but that is a different animal all together. thanks for the education.
Posthole Digger Hydraulic post hole digger
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JRP
Platinum Member
<font color="blue"> </font>" In a typical application
running the pump at reduced flow will simply scale back the torque in direct relation to the speed."
<font color="black"> </font> This seems wrong. I think with a hydraulic motor that torque would be proportional to pressure and both horsepower and speed is proportional to flow. Running the pump at reduced flow will maintain torque but simply scale back the horsepower (and speed) in direct relation to the flow. Like a steam engine, you should still get high torque at low flow and high pressure.
The consequence of not enough horsepower is that you will just take longer to drill the hole. I have watched the hydraulic units drill very large holes at very slow speed. With a Bobcat you also get very good visibility.
running the pump at reduced flow will simply scale back the torque in direct relation to the speed."
<font color="black"> </font> This seems wrong. I think with a hydraulic motor that torque would be proportional to pressure and both horsepower and speed is proportional to flow. Running the pump at reduced flow will maintain torque but simply scale back the horsepower (and speed) in direct relation to the flow. Like a steam engine, you should still get high torque at low flow and high pressure.
The consequence of not enough horsepower is that you will just take longer to drill the hole. I have watched the hydraulic units drill very large holes at very slow speed. With a Bobcat you also get very good visibility.
uhmgawa
Gold Member
</font><font color="blue" class="small">( <font color="red">In a typical application
running the pump at reduced flow will simply scale back the torque in direct relation to the speed."</font>)</font>
</font><font color="blue" class="small">( This seems wrong.)</font>
That statement is quite wrong. Here is what I attempted to convey:
Torque is proportional to the product of motor displacement
and differential pressure seen by the motor. As the motor
displacement is constant and the maximum pressure is the
system limit, the torque [ideally] is constant. In a typical
application running the motor at reduced flow will simply
scale back the work developed per unit time [ie: HP] in direct
relation to the rotational speed.
running the pump at reduced flow will simply scale back the torque in direct relation to the speed."</font>)</font>
</font><font color="blue" class="small">( This seems wrong.)</font>
That statement is quite wrong. Here is what I attempted to convey:
Torque is proportional to the product of motor displacement
and differential pressure seen by the motor. As the motor
displacement is constant and the maximum pressure is the
system limit, the torque [ideally] is constant. In a typical
application running the motor at reduced flow will simply
scale back the work developed per unit time [ie: HP] in direct
relation to the rotational speed.
