Prony brake calculation help (for determining engine horsepower)

Click For Summary
SUMMARY

The discussion focuses on calculating horsepower using a Prony brake setup, specifically with a torque reading of six pounds at four inches from the axle centerline and a rotational speed of 30 RPM. The formula used for conversion is HP = Torque x RPM / 5,252, which was adapted to calculate power in watts and subsequently converted to horsepower. The final calculation resulted in approximately 0.0115 HP. Participants clarified terminology and provided detailed calculations to assist in understanding the process.

PREREQUISITES
  • Understanding of torque measurement in foot-pounds
  • Basic knowledge of rotational speed in RPM
  • Familiarity with the Prony brake principle
  • Ability to perform unit conversions (e.g., pounds to kilograms, watts to horsepower)
NEXT STEPS
  • Research the Prony brake method for measuring engine horsepower
  • Learn about torque conversion and its implications in mechanical systems
  • Explore the use of calculators for torque-to-horsepower conversions
  • Investigate the effects of angular velocity on power calculations
USEFUL FOR

Engineers, mechanics, and automotive enthusiasts looking to understand horsepower calculations and the application of Prony brakes in performance testing.

Pinon1977
Messages
126
Reaction score
4
TL;DR
I need some help here. I'm trying to determine how to use the numbers I'm getting for my pony break to determine horsepower at the axle of my engine. Right now I'm getting a reading of six pounds of torque, 4 in off of the center line of the axle at a rate of 30 rpms. Can someone help me determine what the horsepower is here?
I need some help here. I'm trying to determine how to use the numbers I'm getting for my pony break to determine horsepower at the axle of my engine. Right now I'm getting a reading of six pounds of torque, 4 in off of the center line of the axle at a rate of 30 rpms. Can someone help me determine what the horsepower is here?
 
Physics news on Phys.org
HP = Torque x RPM / 5,252

Torque is in foot pounds.
 
6 pounds of torque, 4 in from the center line of the axle, at 30 rpm.
Let us know your setup and how you measure 6 pounds.

6 pounds = 2.721 kg. If pounds are a weight, then
convert to force 2.721 * 9.8 = 26.7 newton.
4 inch = 0.102 metre. Torque = 26.7 * 0.102 = 2.723 Nm.
30 RPM = 0.5 rev/sec. Angular velocity = 3.1416 rad/sec.
Power = 2.723 * 3.1416 = 8.555 W.
HP = 8.555 / 745.7 = 0.0115 HP.
 
Baluncore said:
I assume by "pony break" you mean "Prony brake".
https://en.wikipedia.org/wiki/Prony_brake

I used to think it was a pony brake. I mean, it does make sense that you would measure horsepower on a pony brake.

Edit: Maybe use a pony to calibrate it?
 
  • Like
Likes   Reactions: weirdoguy and SammyS
Yes you would assume correctly. Proney. Stupid voice to text misspelled it for me. That's what I get for not proofreading. Haha. Anyhow thanks for the feedback. Much appreciate itQUOTE="Baluncore, post: 6893999, member: 447632"]
I assume by "pony break" you mean "Prony brake".
https://en.wikipedia.org/wiki/Prony_brake
[/QUOTE]
 
Baluncore said:
6 pounds of torque, 4 in from the center line of the axle, at 30 rpm.
Let us know your setup and how you measure 6 pounds.

6 pounds = 2.721 kg. If pounds are a weight, then
convert to force 2.721 * 9.8 = 26.7 newton.
4 inch = 0.102 metre. Torque = 26.7 * 0.102 = 2.723 Nm.
30 RPM = 0.5 rev/sec. Angular velocity = 3.1416 rad/sec.
Power = 2.723 * 3.1416 = 8.555 W.
HP = 8.555 / 745.7 = 0.0115 HP.
Hello there. This is the feedback I was looking for. Thank you!
 
  • Like
Likes   Reactions: Baluncore

Similar threads

  • · Replies 31 ·
2
Replies
31
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 7 ·
Replies
7
Views
7K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 2 ·
Replies
2
Views
4K
Replies
26
Views
6K
  • · Replies 10 ·
Replies
10
Views
7K
  • · Replies 7 ·
Replies
7
Views
4K