Piston Definition and 394 Threads

A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.

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  1. K

    Resultant force on the piston at the end of stroke

    Homework Statement my question is on part a , the ans is 4260N . but my answer is double of the ans given. why I'm wrong? the working is shown in the photo. Homework Equations The Attempt at a Solution
  2. M

    Simulation of Compressed Air Driven Piston

    I am writing a MATLAB script that generates a dynamic simulation of a piston being driven by compressed air. My starting values for pressure and volume are as follows: P0 = 14000000; %nm-2 or 140 Bar V0 = 0.005; %m3 or 500cc The simulation needs to be quite detailed and must take into account...
  3. steves1080

    Question on positive displacement piston pumps

    This is a very simple question but I am struggling to grasp the answer. My question is in regards to a positive displacement piston pump. http://upload.wikimedia.org/wikipedia/en/thumb/0/0d/Axial_piston_pump.svg/686px-Axial_piston_pump.svg.png Say you are using this machine to pump...
  4. Y

    How to Create a Cheap Piston with Arduino and Control Movement?

    Hi, I am a total beginner on all subjects of engineering, but I do want to ask here if it's the right place, about this project I want to do: I want to create a cheap (as cheap as possible, home-made kind of thing) piston that will simply move in a linear way in and out (about 40-50cm movement...
  5. A

    Deriving motion of a displaced piston on a gas cylinder

    First, I'm a second year high school physics student so my thinking may be half-baked. I was wondering what motion a piston would exhibit if it was the frictionless lid of an ideal gas cylinder with a constant amount of air, and if it was pushed or pulled a little bit. There would be a...
  6. E

    Tolerance for pneumatic cylinder and piston

    What is the tolerance for pneumatic cylinder and piston operating about 2 psi, at room temperature, so that the piston can move freely without leakage? The piston diameter is 20 mm.
  7. B

    Thermodynamics sealed piston Problem

    Homework Statement You have a sealed piston with a VERY LIGHT and moveable top that can easily slide up and down without friction. It starts at room temperature with 1 kg of water in the bottom. You heat it, boil the water, and further heat the water until it is at 150°C. Determine the...
  8. U

    Find the equilibrium position of this piston

    Homework Statement A portion of helium gas in a vertical cylindrical container is in thermodynamic equilibrium with the surroundings. The gas is confined by a movable heavy piston. The piston is slowly elevated a distance H from its equilibrium position and then kept in the elevated position...
  9. M

    Isothermal Process in a Non-Insulated Piston: Heat Exchange?

    When an ideal gas expands in a piston during an isothermal process, does it necessarily absorbs heat from the surroundings in order to maintain its temperature? (Piston is not insulated). IF yes, When the same procedure is carried out in a perfectly insulated piston, then temperature drops...
  10. Saitama

    Thermodynamics problem - weight and piston connected by string

    Homework Statement An easily moveable, thermally insulated piston of negligible mass confines a sample of air of volume ##V_0=8\,\, \text{litre}##, at a temperature of ##T_0=300 K##, into a thermally insulated cylinder of cross section ##A=1\,\,dm^2##. The cylinder is fixed to a horizontal...
  11. W

    Damping Force in a piston: Ideal Gas versus a Fluid

    I was in my physics of the human body class and we got on the topic of pistons. It was given to me that the dampening force pertaining to such a piston filled with a gas is proportional to the square of the velocity of the piston; however, for fluids it was given as simply proportional to the...
  12. N

    A piston with adjustable resistance?

    Dear all, I have recently come across a project that requires me to find a device that does the following, A device that: 1)generates "0" movement 2)have a shaft that can be pulled or pushed over a distance 3)I can induce a variable resistance force to the shaft (to counter external...
  13. A

    Work, heat, thermodynamics Cylindric Piston

    Consider 5.5 L of a gas at a pressure of 3.0 atm in a cylinder with a movable piston. The external pressure is changed so that the volume changes to 10.5 L. a) Calculate the work done, and indicate the correct sign. b) Use the preceding data but consider the process to occur in two steps. At...
  14. T

    Linear force generated by a piston of varying diameter & stroke

    Hi, I'm not an engineer but I do dabble in working out solutions to engineering problems in the manufacturing environment. I am working on a project/idea at present and I need to be able to calculate the height that a single piston and cylinder, internally combusting, can project a 100kg weight...
  15. M

    Momentum delivered to a piston

    Okay so please forgive the simple question - I am slowly educating myself but find that sometimes the intuitive view evades me. In Feynmans Chapter 38 of Vol 1 - I am reading through kinetic theory of gases about the momentum of a particle hitting a static piston. The section after 39.2. He...
  16. P

    How to suddenly stop a gear? (or how to suddenly stop a moving piston)

    Hey, I'm trying to design a part for a prosthetic leg. I need to stop a piston moving within a cylinder at any point in its motion. (this will happen when the patient puts weight on his foot) I was thinking about having the piston turn a gear, and then when it's time to stop it, another...
  17. I

    Required force to rotate the Engine piston

    Dears, please help me: How to Calculate the Required Force to Push the Car Engine Piston Down if I Want to Rotate my shaft in 1500rpm, My Piston Dia Is 50mm, Piston Hight Is 100mm, Piston Mass Is 1kg, My Engine Is 4cylender and 4stroke? regards ibrahim
  18. Gh778

    Liquid helium and curved piston

    It's a theoretical study. Like the image showing, the curved piston move in container and need energy for that. In the same time, another piston move up and recover energy. The pressure inside container is always the same (need to control speed of pistons, but there is a pressure). No gravity...
  19. H

    Piston problem -- Method to increase the force against a spring

    Hi people, I need help to this problemSomeone has suggested that the device shown in the figure below be used to improve the maximum force F against the spring, which has a spring constant of k. This is accomplished by changing the temperature of the liquid-vapor mixture in the container. You...
  20. C

    How Much Does a Car Rise on a Hydraulic Lift?

    Homework Statement A hydraulic car lift has a reservoir of fluid connected to two cylindrical fluid filled pipes. The pipe directly below the car has a diameter of 1.8 m. the pipe o which the plunger acts has a diameter of 0.045m. the plunger is depressed a distance of 1.5m. How much does the...
  21. C

    Oil volume required to rise the piston

    Homework Statement The piston shown weighs 11 lbf. In its initial position, the piston is restrained from moving to the bottom of the cylinder by means of the metal stop. Assuming there is neither friction nor leakage between piston and cylinder, what volume of oil (S = 0.85) would have to...
  22. R

    Exploring the Pressure Change in a Cylinder w/ Piston

    Homework Statement Given below is a cylinder with piston with same area at both the ends. The cylinder holds pure water in it. If force F is applied from both the ends, find the change in pressure at point B.Ignore Atmospheric Pressure 2. Diagram The Attempt at a Solution...
  23. S

    Cylinder w/Piston: Final Temp & Vol Answered in Terms of Nk, T0, V0

    Homework Statement A cylinder is closed at both ends and has thermally insulating walls. It is divided into 2 parts (left and right) by a movable, frictionless, thermally insulating piston. There is a heating coil in the left compartment, and there are N molecules of an ideal gas, with heat...
  24. B

    Solving the Mystery of Vacuum in a Cylinder with a Piston

    Hi all, i was pottering away at work yesterday and realized just how little i truly understand about vacuum! So i have a question, i have a piston in a cylinder, the piston is fully in the cylinder so there is very little air space and the cylinder port is blocked off, the piston has an area of...
  25. M

    Work done on condensing steam in a piston

    Homework Statement A cylinder has a well fitted 2.0Kg metal piston whose cross-sectional area is 2.0cm^2. The cylinder contains water and steam at constant temperature. The piston is observed to fall slowly at a rate of 0.30cm/s because heat flows out of the cylinder walls. As this...
  26. K

    Modelling heat loss to cylinder walls in a piston engine.

    I am building a mathematical model of a piston engine which calculates the pressure and temperature of the cylinder gas every 1° of crank angle. I'm having some difficulty with the heat transfer to and from the cylinder wall (to when the Tg > Tw and from when Tg < Tw). I found the heat...
  27. N

    Piston Ring End Gap: Are We Doing It Right?

    Im an intern at a manufacturing company looking at whether our end gaps are too small on piston rings. Can someone take a look at this and tell me if I'm doing it right? We have a piston ring that goes into a 9 5/8" bore. The upper limit of the end gap is 0.136. Max temperature is 300°F. For...
  28. D

    Expansion of a gas against a piston

    So let's say a gas is doing some work against a piston and decreasing its internal energy. Does the gas also do work against gravity if it is expanding in the positive y direction? If so would it even be measurable? Thanks for the help
  29. A

    Ideal Gas & Piston Homework: Calculate Distance Moved

    Homework Statement Asshown in the figure below, an enclosed cylindrical container(cross-sectional area : S) is divided into two sections (A,B) by piston P.The length of each section is 10cm.Each section contains a monoatomic gas at temperature 0°C and pressure 1.0×10^5 Pa.(both contain the...
  30. N

    Change in u and h is for a piston cylinder device.

    Homework Statement 0.03m^3 of air is contained in the spring-loaded piston-cylinder device. The spring constant is 875N/m and the piston diameter is 25cm. When no force is exerted by the spring on the piston the state of the air is 2250kPa and 240C. This device is now cooled until the volume is...
  31. marellasunny

    Design of 4 stroke IC engine from few parameters (bmep, B.P, piston speed)

    (I have trouble in finding the stroke length and fuel flow rate) From Heywood,E2.11 You are designing a 4 stroke CI to provide a brake power of 300kW,Naturally aspirated at its max rated speed.Based on typical values for brake mean eff.pressure(bmep){700kPa to 900kPa} and max mean piston...
  32. T

    Dimensions for a Steam Piston Valve

    Hello, I'm Nate, and I'm looking to build a compressed-air engine. I'm using a pneumatic cylinder with a 3" bore and a 12" stroke. That was simple enough to find. What hasn't been simple to find is a manual valve large enough to actuate it. I've found small 5-way valves on ebay and amazon, but...
  33. M

    Thermodynamics: Piston and Cylinder

    Homework Statement A piston-and-cylinder device contains 5 kg of water initially at 150◦C and 0.20 MPa. The frictionless piston is then pushed slowly in an isothermal process until the volume of water becomes 10% of its initial value. Calculate the heat and work exchanged between the device...
  34. G

    Piston Conundrum: Does it Move?

    Homework Statement In the picture below, the pressure on either side of the piston is equivalent. The question asks which direction the piston moves (or if it even moves at all). http://imageshack.us/a/img203/1830/photoon3613at919pm.jpg Homework Equations P1*V1 = P2*V2 = C P =...
  35. S

    Ideal Gas in a Cylinder with Piston

    Hey, I'm trying to come up with a question, be it a simple one, where a mass of ideal gas (Oxygen) is bound in a cylindrical tube and has a circular piston applied to it - so that the gas becomes pressurised. Once the gas has been pressurised it will gain a certain temperature, which is the...
  36. T

    Why Does the Textbook Solution Use Average Pressure for Piston Work Calculation?

    Homework Statement Here is the solution from the textbook: I don't understand how they can assume a linear relationship. In fact I don't even understand the math... Why does the solution take the average pressure? Isn't the relationship between pressure and volume PV^n = constant?
  37. B

    How to calculate force needed to push piston based on crankshaft value

    Homework Statement How do you calculate the force needed to push against a piston based on the mass of the vehicle, the rpm of the crankshaft, radius of crankshaft (same distance as the center of the crankshaft to the attachment point of the connecting rod and the crankshaft), and the length...
  38. T

    Isothermal and Adiabatic piston problems

    Homework Statement This is Problem 12.5 in Blundell's Thermal Physics book. Two Thermally insulated cylinders, A and B, of equal volume, both equipped with pistons, are connected by a valve. Initially A has its piston fully withdrawn and contains a perfect monatomic gas at temperature T...
  39. T

    Two gases in a cylinder separated by an insulating piston.

    Homework Statement A cylinder of cross-sectional area A is divided into two chambers 1 and 2, by means of a frictionless piston. The piston as well as the walls of the chambers are heat-insulating, and the chambers initially have equal length L. Both chambers are filled with 1 mol of helium...
  40. S

    ThermoDynamics: piston arrangement with stoppers

    Right, I might be dumb, or whatever, but I've pondering for a while and it's annoying because I feel like there is not enough information (too many unknowns not enough equations) Homework Statement The piston/cylinder arrangement shown Fig Q3 contains air at a pressure of 2 bar and a...
  41. C

    Work done by gas expansion on piston

    Homework Statement Consider a frictionless piston inside a cylinder, both with a cross sectional area A. 1) By considering the work done by the gas on the piston and the work dW required to move the piston a distance dx, show that the work done by the gas is dW = -pdV. 2) 1 L of an ideal...
  42. O

    Propane Combustion (btu/ft^3) how fast it'll move a piston

    I hope I can make this understandable. I'm working on a design to utilize combustion of propane to cycle a piston. I'll attach a gif to make it more simple to understand. When the cylinder is filled with an ideal 4% of propane (green) it'll combust (turns yellow) to push back the cylinder...
  43. V

    Pressure of piston in a cylinder containing gas, find heat (Q)

    Homework Statement A cylinder of cross-sectional A is filled with N ideal gas molecules at temperature T and pressure p, and a piston of mass m seals the gas in the cylinder with a frictionless seal, as shown on the figure attached. The trapped column of gas has an initial height h. The piston...
  44. T

    Hydraulic piston break system problem

    Homework Statement The figure below shows the essential parts of a hydraulic brake system. The area of the piston in the master cylinder is 1.8 cm2, and that of the piston in the brake cylinder is 6.4 cm2. The coefficient of friction between shoe and wheel drum is 0.50. If the wheel has a...
  45. N

    16 inch piston with a 4 inch outlet

    If I had a 16 inch piston in a 16 inch by 60 inch cylinder( they fit and are water tight). It is standing on its end At the bottem I have a 4 inch outlet pipe with 2- 90's and a pipe going back up 40 feet How many pounds would I need to put on the 16 inch piston to push the piston all the...
  46. I

    Eliminating Piston Oscillation with PID Control in Electropneumatic Systems

    Hello everyone! We have built the following model with Automation Studio. It's a simple electropneumatic system with a 4/3 valve and a piston. I would like to eliminate the oscillation of the piston with a PID controller. Does anyone know how to do it? Thanks
  47. M

    Adiabatic gas Compression of Piston after Critical Point

    Hello there, Sorry, if there's a thread about this already. Let's say if i have Piston which is fully insulated because as mentioned, it is an adiabatic compression. The pressure will increase as the volume of decrease. But what really happened when the system is compressed over the...
  48. N

    Thermodynamics Hw help, piston designing

    Homework Statement Have a design project in thermodynamics. The problem reads, Someone has suggested that the device shown in the figure below be used to improve the maximum force F against the spring, which has a spring constant of k. This is accomplished by changing the temperature of...
  49. A

    Thermodynamic - water/ice piston help

    An inventor proposes to make a heat engine using water/ice as the working substance inside a cylindrical piston and taking advantage of the fact that water expands as it freezes and can therefore lift a piston supporting some mass m. The engine process consists of four steps as shown in the...
  50. K

    Bulk Modulus, Expansion Coeff. and compression of a liquid in a piston

    Homework Statement A liquid is enclosed in a metal container that is provided with a piston of the same metal. The system is originally at a pressure of 1.00 atm (1.013*10^5 Pa) and at a temperature of 30.0 C. The piston is forced down until the pressure on the liquid is increased by 50.0 atm...
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