Jump to content
Sign in to follow this  
BairleaFarm

Hydro question

Recommended Posts

BairleaFarm

How many RPMs does the Hydro pump need to turn at full throttle? Im sure it can be figured out biased on pulley diameters but I have no idea how to do that.

Share this post


Link to post
Share on other sites
 
illinilefttackle

:USA: David- I trust that the engineers at Wheel Horse (when there was a Wheel Horse) had that all figured out-right pulley sizes etc. I was told to run my Hydro at 3/4 throttle or higher to insure the pump getting cooled properly. RPM'S- :banghead: -AL

Share this post


Link to post
Share on other sites
 
wh500special

I'd bet there is a reference to this speed in the rebuild manuals, but none of that stuff is handy for me right now...

Al is right about running the hydro at rated speed too...when operating the tractor, run the engine at wide open (or close to it). I think it is actually a pressure issue though, and not just a cooling issue. Doesn't matter, with a hydro run full steam on the engine.

On the D-auto tractors the hydrostatic pump is coupled directly to the engine and turns at the same speed as the engine. Which, of course, should be 3600 rpm at full blast.

I had to mess with my C160 this morning and actually tried to measure the speed at the pump with an old hand tachometer I have...2200 rpm at full engine speed. I guess the pulley on the engine is smaller than that on the pump - or my tachometer is off.

The speed calculation is simple, just remember that the linear speed of the belt is the same on every pulley in the system to which it is connected. If one pulley in the system is - for example - 4" diameter and the other is 2" diameter and the larger of the two is spinning at 1000 rpm, then the smaller will spin at 2000 rpm. Set it up this way:

(RPM on Pulley #1)*(Diameter of Pulley 1)=(RPM on Pulley 2)*(Diameter of Pulley 2)

It's 6th grade algebtra from here..just plug in the three values you know and solve for the third...for my example above assume:

RPM pulley 1 = 1000

Diameter Pulley 1 = 4

RPM pulley 2 = RPM this is what we need to solve for

Diameter Pulley 2 = 2

substituting...

(1000)*(4)=RPM*(2)

doing the arithmetic....

4000 = RPM*2

solving for RPM, so divide both sides by 2...

4000/2 = RPM

simplify....

2000 = RPM

This, obviously, assumes no slippage of the belt on the pulley. And you MUST keep your units of measure the same (i.e. Both diameters must be in inches, or both must be in millimeters, or both must be in lightyears, etc) and the speeds must both be in RPM (or both must be in rad/s, etc.). If you mix and match units, your results will be wrong and meaningless.

I guess you could re-write this expression like this...

RPM2 = (RPM1)(Diameter1)/(Diameter2)

where the #'s 1 and 2 denote pulleys #1 and #2 respectively. If you have more than two pulleys in your system, just step though the system taking two pulleys at a time. If you want to determine what diameter pulley you need to do soemthing, just rearrange the equation to give you that result:

Diameter2 = (RPM1)*(Diameter1)/RPM(2)

IF you want to calculate the belt speed (linear speed in, say, inches per minute) for some reason, you need to call up a little geometry and incorporate pi....

Belt Speed (inches/minute) = (RPM of pulley)*(diameter of pulley in inches)*(3.14)

if you want THAT number in feet per minute - which is a pretty standard way of measuring belt speed - divide the result by 12...

Belt Speed (feet/minute) = (RPM)*(Diameter)*3.14/12

I will be majorly embarrassed if I blew this :banghead: ...but it looks right at a glance :USA: .

Steve

Share this post


Link to post
Share on other sites
 
linen beige

I'd bet there is a reference to this speed in the rebuild manuals, but none of that stuff is handy for me right now...

Al is right about running the hydro at rated speed too...when operating the tractor, run the engine at wide open (or close to it). I think it is actually a pressure issue though, and not just a cooling issue. Doesn't matter, with a hydro run full steam on the engine.

On the D-auto tractors the hydrostatic pump is coupled directly to the engine and turns at the same speed as the engine. Which, of course, should be 3600 rpm at full blast.

I had to mess with my C160 this morning and actually tried to measure the speed at the pump with an old hand tachometer I have...2200 rpm at full engine speed. I guess the pulley on the engine is smaller than that on the pump - or my tachometer is off.

The speed calculation is simple, just remember that the linear speed of the belt is the same on every pulley in the system to which it is connected. If one pulley in the system is - for example - 4" diameter and the other is 2" diameter and the larger of the two is spinning at 1000 rpm, then the smaller will spin at 2000 rpm. Set it up this way:

(RPM on Pulley #1)*(Diameter of Pulley 1)=(RPM on Pulley 2)*(Diameter of Pulley 2)

It's 6th grade algebtra from here..just plug in the three values you know and solve for the third...for my example above assume:

RPM pulley 1 = 1000

Diameter Pulley 1 = 4

RPM pulley 2 = RPM this is what we need to solve for

Diameter Pulley 2 = 2

substituting...

(1000)*(4)=RPM*(2)

doing the arithmetic....

4000 = RPM*2

solving for RPM, so divide both sides by 2...

4000/2 = RPM

simplify....

2000 = RPM

This, obviously, assumes no slippage of the belt on the pulley. And you MUST keep your units of measure the same (i.e. Both diameters must be in inches, or both must be in millimeters, or both must be in lightyears, etc) and the speeds must both be in RPM (or both must be in rad/s, etc.). If you mix and match units, your results will be wrong and meaningless.

I guess you could re-write this expression like this...

RPM2 = (RPM1)(Diameter1)/(Diameter2)

where the #'s 1 and 2 denote pulleys #1 and #2 respectively. If you have more than two pulleys in your system, just step though the system taking two pulleys at a time. If you want to determine what diameter pulley you need to do soemthing, just rearrange the equation to give you that result:

Diameter2 = (RPM1)*(Diameter1)/RPM(2)

IF you want to calculate the belt speed (linear speed in, say, inches per minute) for some reason, you need to call up a little geometry and incorporate pi....

Belt Speed (inches/minute) = (RPM of pulley)*(diameter of pulley in inches)*(3.14)

if you want THAT number in feet per minute - which is a pretty standard way of measuring belt speed - divide the result by 12...

Belt Speed (feet/minute) = (RPM)*(Diameter)*3.14/12

I will be majorly embarrassed if I blew this :banghead: ...but it looks right at a glance :USA: .

Steve

Yes, What he said!

Share this post


Link to post
Share on other sites
 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...