A observation about HP management...

[DEWFPO]

As I understand it, the HP mgmt. feature on the Toolcat tries to keep engine RPM (and consequently hydraulic pump rpm) as high/or as constant as possible 'under load', so that the hydraulic pressure/flow is maintained to power the attachments adequately, at the expense of speed (mph). That makes sense. There's no sense in going fast if your mower deck isn't spinning fast enough to provide a good, clean cut.

It is interesting that when climbing steep inclines, when no attachment is powered up, the HP mgmt. does atempt to maintain engine rpm, but speed still declines. I'm assuming the hydraulic flow to the drive system is greater than the HP mgt. system can adjust for. Even with the Hi-Flow option.

Any thoughts?

DEWFPO

 

[3Bladz]

I am not really sure what is going on either. When I am on the road every little incline slows it down to 10 or 12 mph with some decrease in RPMs. I'll have to try it and see how much the rpms drop. How much should it allow the rpms to drop before slowing the speed? It is really wierd when you start letting up on the pedal and the rpms rise it almost feels like it starts moving faster before it slows down. Do you know what your rpms are at top speed on level ground versus a slight grade? My hydrostat tractor slows a couple mph but not 40% and it has less hp. It has hp management too.

 

[radman1]

My belief is the hp management is almost completely based on engine rpm. It will do whatever it needs to the hydraulic flow in the drive motors to maintain the rpm. It is like my load match on my Jd CUT. Dig into a pile of dirt, the HST compensates for lower engine rpm by turning the wheels slower. No different with the TC. My CUT will slow and speed up when doing tasks such as traveling down roads, pulling trailer ect. However, on the CUT, I can turn off the load match (hp management) by flipping a switch. I actually turn if off most of the time and let my foot on the HST pedal be the "management". I don't like the noticable varibility in speed as I do most tasks. I don't mind letting the engine work a little harder, if the task will be relatively brief. I don't let the engine bog down, but max hp and torque for diesel is often in the 1800-1900 rpm and not at the operating/pto 2200-2400 rpms of many diesels.

My ag tractor has a little different version of hp management call constant engine speed. I can manually set the engine rpms and make the tractor stay between a specific range, say 1700-2100 rpms. If it falls below 1700 rpm, it will automatically downshift, if above, it will upshift. I don't use it but someone who bales hay or sprays with pto pump may find it useful. I can also set the rpms to automatically downshift if the rpms drop 10%, 15%, 20%, 25% or 30%. Once power is regained it will automatically upshift again. This will work either in heavy tillage or traveling on the road.

 

[DEWFPO]

I am not really sure what is going on either. When I am on the road every little incline slows it down to 10 or 12 mph with some decrease in RPMs. I'll have to try it and see how much the rpms drop. How much should it allow the rpms to drop before slowing the speed? It is really wierd when you start letting up on the pedal and the rpms rise it almost feels like it starts moving faster before it slows down. Do you know what your rpms are at top speed on level ground versus a slight grade? My hydrostat tractor slows a couple mph but not 40% and it has less hp. It has hp management too.

I don't have any flat ground or roads around here (seriously). My SCUT had no HP mgmt. and in high gear going up the same inclines would only slow down a bit but not bad. No bucking.

DEWFPO

 

[melgibson]

DEWFPO:

If possible, I'd like to speak with you offline. Is there a way that I can contact you?

 

[J_J]

I believe that a hydrostatic transmission, will develop a given torque at a certain speed for the wheel motors as in my Power-Trac. When you go up an incline, you are imposing more force, that the engine has to overcome, so most people will push down on the hydro pedal thinking that will give more speed. What you should do is to let off the pedal and keep the torque up, although at a lower speed.

A log splitter work similar as to torque and speed. The pump is pumping a given volume, and when the wedge starts working hard, the pump shifts to low flow, more torque, and time to cut is increased.

 

[DEWFPO]

DEWFPO:

If possible, I'd like to speak with you offline. Is there a way that I can contact you?

PM sent yesterday.

DEWFPO