Track Powered Car

I'd look at some equivalent vehicles already on the market and follow their lead.

They probably have engineers who have already done these calculations.

You mean like this??

There needs to be some further information, such as track drive sprocket pitch diameter, motor rpm limitations, and ratio of any reduction gearing.

One intermediate calculation will involve 5000 sin 25º ≈ 2113 lb.

I am using a 7.14 in dis sprocket driving the track. I already too into account the angle for the additional torque requirement. Rpm on the motor is about 160 RPM so that I can get 7 mph. I am not thinking on using a gear reduction gearbox since I can find a Low Speed High Torque Motor to use. I only using one HYD motor per track and they will be controlled with independent sections of a pump. not doing hydro stat pump, open loop with electronic controls.

Hope this makes it easier to understand what i am trying to do.

Given your 2113 pound estimate I am coming up with a per track axle torque of ~ 750 Ft/Lbs per track to get 7 MPH on a 25 Degree slope and a power input of ~48 HP gross as bare minimums.

That seem reasonable to you?

That seams a bit too high, is that because of being a track system? I will attach my excel sheet tomorrow in how I got to the numbers I got. Please remember those are based on a wheel system not tracks. I have been doing those for a long time and everytime I have had success!

For static holding force only, I'm coming up with 296 lb-ft per track. For HP @ 7 mph horizontal (287 ft/m vertical), I get 43.5. These numbers are rounded off, of course, and I may recheck them tomorrow.

That seems about right. I've been around hydraulic systems and their calculations Vs real world results when working with likely less than perfectly match pump valve and motor components to enough to know to always round off high and estimate a bit higher yet.

So 43.5 + ~10% would land within working range my 48 HP estimate.

I didn't specifically account for efficiency, which could correct my estimate even closer into your range.

These are my calculations (If using wheel based vehicle equations). Also, these are per track so total HP needed would be times 2. What am I forgetting that my HP needed seems to be lower than what your coming up with.

It is quaint to see imprecise numbers carried out to three decimal places. GIGO at its best.

Maybe some help here....

http://machinedesign.com/mechanical-drives/hydrostatic-drives

https://www.finaldriveparts.com/

http://www.womackmachine.com/engineering-toolbox/design-data-sheets/force-required-to-accelerate-a-load.aspx

http://www.womackmachine.com/engineering-toolbox/formulas-calculations/hydraulic-motor-calculations.aspx

Are you going to make scale models, or go full scale right off the bat?

Can you test with electric motors?

Pretty much, IHNI, but it seems to me you mentioned 2 motors per track, is that right? Four motors in all, but how do you ensure they are in sync?

By the fact that they are connected to the same track?

OK, but if one is picking up more HYD than the other, does not one become the driver and the other the driven?

they would not be connected to the same track, each motor has a sprocket connected to their respective track. Using a 7.14 diameter sprocket and each motor is being supplied with oil by independent sections of the pump electronically controlled.