The Little Pump that Could

1
The Little Pump that Could
ME 3580, Mechanism Analysis
November 21, 2005

• By Everett Bolduc
• Martin Grashik
• Justin Rensch
• Steve Yurk

2
Abstract

• The oil pump is a simple mechanism that
  oscillates up and down to draw oil out of the
  ground. The task of this project was to analyze
  the oil pump, find the degrees of freedom, and do
  a position, velocity, and acceleration analysis
  on it. We first identified the mechanism as a
  four-bar linkage, defined critical parameters and
  dimensions, then applied the appropriate
  equations.

3
Introduction

• Use of Mechanism
• The objective of the oil field pump is to
  convert the circular motor input into a smooth
  oscillatory rocking motion that can be utilized
  to draw crude oil out of the ground. To achieve
  this motion the pump uses a four bar system
  consisting of ground, a crank, pitman arm, and a
  balance beam. The balance beam can be adjusted
  with weights to reach the most efficient
  oscillatory motion that will also have the least
  wear on the motor.

• Critical Parameters
• Some critical parameters that should be
  consider for the oil field pump are the frequency
  of the rocking motion, proper weight and balance,
  and thus position of the links, and also the
  dimensions of the links to insure proper
  amplitude of motion. All of these parameters need
  to be defined to produce the needed pressure to
  pump the oil, and to have the least amount of
  strain and energy input to the motor. An analysis
  of the oil field pump will help define
  quantitatively what these critical parameters
  are.

4
Drawing of Mechanism
Dimensions in inches
5
Degrees of Freedom
from Greublers Equation
Mobility 3L 2J 3G Where L of Links,
J Number of Joints, G Number of ground
Links M 3(4) - 2(4) - 3(1) 12 8 3
1 D.O.F. 1
6
Position Analysis
Analytical
All angles in radians
7
Position Analysis
Graphical
?2 327 5.707rad ?3 -33 -0.576rad
?4 269 4.695rad -1.588rad ?P 71
1.239rad
8
Velocity Analysis
9
Acceleration Analysis
10
Results

• To obtain values for the positions, velocities
  and accelerations we used the equations from the
  Design of Machinery textbook, programmed into
  Microsoft Excel.
• A rough drawing in and graphs from Working Model
  2D are shown at right for the motion of point P
  (shown in the drawing)
• The motion is oscillatory between two extreme
  values.

11
Conclusion and Recommendations

The amplitude of point P was found to be 27.12
inches, or about 2 feet. This seems like a
reasonable pumping distance per revolution of the
crank arm because you dont want to have the
engine pulling up too much oil per revolution.
This parameter can not be too large since the
pumping amplitude is directly related to the
volume of oil pumped. One recommendation we could
offer would be to keep the center of gravity of
the rocker arm directly above the support
(designated point D on the AutoCAD drawing).
This would create less wear and tear on the
engine by making it easier for the coupler to
push the rocker up and down.
12
Resources

• AutoCAD 2006. San Rafael, CA Autodesk Inc.
  (2006)
• Norton R. L. (2004) Design of machinery, Third
  Edition, McGraw-Hill, New York.
• Working Model 2D. Santa Ana, CA MSC. Software
  Corp. (2005).
• Microsoft Office PowerPoint. Redmond, WA
  Microsoft Corp. (2003).
• Microsoft Office Excel Redmond, WA Microsoft
  Corp. (2003).