which piston/rod? #7?

could you explain how this works...to a dumby?? looks cool, just dont understand how it works

 

Basically strain is directly proportional (up to the material yield strain anyway) to the amount of torque applied to it. So if you know the diameter of the material, its material properties, and measure its strain deformation (what Dr.Mike's thing does), you can calculate the torque with a pretty high degree of accuracy. If you also integrate the RPM at which this occurs you can accurately calculate the power since power = torque x rpm.

 

Strain is basically the amount of 'stretching' that occurs to an object when you apply a force to is. A good example is a spring. It 'deflects' a certain % of its length for each unit ( lbs ) of force applied.

Solid metal objects act just like extremely stiff springs. The change in length is measured in 'parts per million' or 'micro-strain'. i.e. if you stretch an object by 1 micro-strain, its length will increase by 1 one-millionth of its original length. 10,000 micro-strain are equal to a change in length of 1%

Strain gages are electro-mechanical devices. They look like postage stamps. The are applied to the surface of a metal object that will be stressed. And they deform along with the object.

They have a resistive metal pattern on them that changes its resistance when stretched. So, the change in electrical resistance is proportional to the deformation or 'strain' on the object.

Unfortunately, the resulting electrical signal is also measured in parts-per-million. So, you need a very special electrical circuit to read it accurately.

From there, the amplified signal is read by a CPU on the PCB that is mounted on the yoke. It transmits the readings using the coil in the pictures.


The system is calibrated by applying a very accurate known force to the object and measuring the actual electrical output. That relationship is stored as the system's calibration.

From this, I can measure the actual torque forces on the yoke to an accuracy of better than +/- 1%. Outside variables, such as vehicle weight, road slope, wind, etc. do not affect the accuracy of the reading.

RPM is read using an infrared optical pickup. Once the torque and shaft RPM are known, HP can be calculated by the standard formula.

HP= torque * RPM / 5252


There is a lot more to it. But, that is the basics.

 

Oh. And, yes. It was #7. Is this a known issue ?

 

...

 

yea...#7 is know to be the weak link and if fueling gets any bit out of wack, #7 pays the price. I am no expert, but thats my take on it

so you divice, is place inbetween the shaft and the Trans, and it is stretched as it applies the TQ to the shaft and rest of the driveline? very cool, its like a coupler that transmits all the tq back, but 'flexes' enough to take a reading and translate it to a understandable measure. refreshing to find innovation in the truck scene(been kind of dieing down)

 

Thanks for the info.

Yes the strain gages are applied to the slip-yoke. I was surprised at what a good signal I was able to read from the big 32-spline shaft. I was actually able to resolve the ~5 ft-lbs I was able to apply by twisting it by hand, while holding it.

I guess this thing could be used in cars as well. But, it seems that the newer Camaro, Mustang, Charger, etc. Don't use slip yokes anymore. I guess I could make a unit that replaces the rubber couplers that they use now, easily enough. The older ones should be a drop-in.

 

Are you finished with R&D yet? They for sale?

 

Yes and no....

The R&D development is complete. Everything is working as expected.

Now it is time for tooling and all the little things that make it an actual product. Things like an a housing for the controller PCB, install program, a user's manual, finalizing the package contents, etc.

I have parts to build up about ten of the prototype units. But, they are only designed for this one application. i.e. I don't have the necessary dimensions to make the adapters for other applications.

If you'd like to be an 'early adopter', and are technically handy, we can work something out. But, I will need some measurements.

 

This is some interesting stuff. Is there a strain gauge in our trans' now that HP Tuners uses for torque output?