Torque calculations for peristaltic pump

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Discussion Overview

The discussion revolves around calculating the torque required for a peristaltic pump driven by a gear arrangement. Participants explore the relationship between input speed, gear ratios, and the force needed from a power spring to maintain a specific output speed. The conversation includes considerations of gear specifications, pump displacement, and pressure, as well as the implications of efficiency on torque calculations.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant calculates that an input speed of 340 rev/min is necessary to achieve an output of 26 rev/min based on a gear ratio of 13.1:1.
  • Another participant suggests that with the same gear ratio, only 2 rev/min input would be needed to achieve 26 rev/min output, indicating a potential misunderstanding of the gear arrangement.
  • There is a proposal to measure torque using the pitch of the gears or their pitch circle diameter/radius, along with a formula involving pressure, displacement, and efficiency.
  • A participant provides a specific example with pressure and displacement values to illustrate how to calculate pump torque, yielding a torque of 200 Nm.
  • Another participant confirms the need for a 340 rev/min input speed and provides the pump's displacement and pressure, noting that efficiency is unknown.
  • A separate query is raised regarding selecting modules for a three-stage reduction gearbox to achieve a total ratio of 40, indicating a different but related topic of gear design.

Areas of Agreement / Disagreement

Participants express differing views on the necessary input speed for the pump, with no consensus reached on the correct calculation method for torque or the implications of gear ratios. Additionally, the efficiency of the pump remains unspecified, contributing to the uncertainty in torque calculations.

Contextual Notes

Limitations include the lack of measuring devices for torque, the unknown efficiency of the pump, and the need for specific gear dimensions to accurately determine torque. The discussion also highlights the complexity of gear arrangements and their impact on performance calculations.

Who May Find This Useful

Individuals interested in mechanical engineering, particularly those working with gear systems and fluid dynamics in pump applications, may find this discussion relevant.

karl8695
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Hi all,

I have a peristaltic pump that i need to rotate at 26 rev/min. The gear arrangement attached to the pump is calculated at 13.1:1 therefore I am assuming an input speed of 340rev/min is required to produce a reduction in speed to the desired output of 26 rev/min.

Gear A (1st driver) - 12 teeth
Gear B (1st driven) - 43 teeth
Gear C (2nd driver) - 9 teeth
Gear D (2nd driven) - 33 teeth

My problem is that I need to know what Force is required to turn my pump and thus the the force required by my drive unit, a 'power spring' to transmit the desired force. I do not have any measuring devices other that a spring scale graduated in Kg. I did however determine the force required to rortate the input shaft, albeit not at the correct speed which came out at an average of 1.8 Kg over 10 tests. I did this by tying a thread around the input shaft to the gear arrangement and then attaching the other end to the spring scale and simply pulling and recording the max pull in Kg over 10 separate attempts.

Can I determine the torque (power) i need from my power spring to turn my pump at a constant speed of 26 rev/min?

Thanks in advance
 
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Some random thoughts:
If the ratio of your gears is 13.1:1 I would have thought the other way. That you only need 2rpm input to get 26 rpm from the pump.

I think to measure the torque you should offer the pitch of the gears or the pitch circle diameter/radius of the gears.

Input torque on the gears should be (torque of pump)/13.1
I think you need to provide the displacement of the pump.

pump torque = ((pressure * displacement)/2pi)* efficiency

eg: pressure = 240 bar
displacement = 55cc
eff = 0.95

T= 200Nm
 
No, the pump definatley works with a geared reduction so 340 rev/min input speed.
Displacement of the pump = 0.3Litres/min
Pressure = 0.1 bar
Efficience is unknown
 
Hey don't know whom to ask but i have a question...
I am using a gear box and its center distances are 70,90 and 120...its a three stage reduction gear box... i want a total gearbox ratio of 40...how should i select the modules i have to use in each 3 stages for getting proper ratio ?
 

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