How many has tried this ~~~~

TWO GUNS · Dec 17, 2007

How many has tried this ~~~~

I must be crazy, or behind time on some things. Talking to the Kubota mechanic today, and being he knows I don't have throttle assist cable. Told me I shoud get one. WHY I ask, he told me that if you set the engine on the rtv at a higher rpm, ( not wide open either ) and lock it, then use your accelerator pedel to go. As we all know, our RTV transmissions run off hydro power, Your transmission pressure is so much higher, that you will have more pulling power and torque. Has anyone tired this, or am I the only one being left in the dark on this way to go >>>>

I ask him want the RTV be running away when you set the rpm up and lock it, even if it's in gear, the answer was no,as long as the pedal was not pressed, for only way the RTV will move, is when you ease down on the accellerator pedal. He said that doing this, a person will only have to barely touch the pedal, and have so much more power & torque, it would suprise anyone.... He also made the statement it will not make the RTV run faster in speed >>>>

Has anyone else tried this.

Hope I explaned this clear enough ~~~~~

KubotaTechnician · Dec 17, 2007

Re: How many has tried this ~~~~

Basically, and without specifics because I don't have the linkage in front of me....

The pedal accelerates the engine AND the hydraulic system. The design is such that as the hydraulics need moreflow from the pump, the engine turns the pump faster. 

So your tech is suggesting that you raise engine speed prior to need in the system. 

(hydraulics lesson)

Hydraulic pumps create flow. Nothing more, nothing less. If you restrict that flow, you have pressure. Pressure does the work.

If the engine creates "x" flow, and the hydraulics use "x" flow, the design is working as planned. If you raise engine speed, and create "x + 2" flow, you will have higher pressure at the hydraulic motor than planned. The higher pressure does exactly what your tech said it could, and adds take off power and "jump". Put enough extra flow to the pump and theoretically tire spinning torque is possible. 

The reason the top end speed of the RTV does not raise is because you won't be exceeding engine governed RPM, and thus cannot exceed hydraulic capacity.You'll achieve faster acceleration to the ground speed that would normally correlate to the engine speed that you set the throttle stop to hold. I'm not sure how much "extra power" you'd gain, and it would only be a gain until you reached the road speed that the engine speed could support.

Ok, so..... In theory this won't hurt your RTV hydraulic system. BUT (disclaimer mode).....

I didn't design the RTV, and I have no control over how any individual modifies his RTV controls. Further, I can in no way speak to the warranty issues that this may present. Do this, and youmay beyour own warranty station. 

Does that explain it?

TWO GUNS · Dec 17, 2007

Re: How many has tried this ~~~~

That's exactly why I ask !!!!!!!!

Did not want to do anything that would damage the RTV..... I just thought this might be something else that I had to learn, like the " Two Stage Tranny " thing, that came to me about a two weeks AFTER the RTV was purchased ~~~

doggman · Dec 17, 2007

Re: How many has tried this ~~~~

Two Guns, 

That's the way most hydro drive equipment works. You set the engine throttle at a constant RPM and vary the ground speed with another control.The governor keeps the engine speed steadywhen you increase the load. Kubota's tractors work that way if they have the hydrostatic trans - HST. 

I think the guy you talked to is probably right. I just didn't realize you could "unsynchronize" the engine speed and the hydraulic motor speed on an RTV. I assumed the throttle assist was strictly for using hydraulic powered tools when the RTV was stopped.

We've been thinking about skidding saw logs with RTV and this might be part of that equation. Another good tip from this forum.

bczoom · Dec 18, 2007

Re: How many has tried this ~~~~

It sounds good in theory but I wouldn't see much benefit myself in the application described.
I would expect that it needs to be disengaged prior to shifting to relieve as much hyd pressure as possible (especially for those of us that don't have the hyd dump control on the dash).
For those in northern climates that have it, how hard is it to control/use with winter gloves on?
Heck, a lot of us have lowered our idle. Why would I want it raised back up (and even higher than how it was origionally set?

KubotaTechnician · Dec 18, 2007

Re: How many has tried this ~~~~

Idle speed shouldn't have anything to do with engaging the gears. Having a high idle won't spin the trans faster, or slower. 

The system that drives the trans is "hydrostatic", which means very little to most. But here goes....

The engine spins a set of pumps. One is a "gerotor" type, which is a set of gears, concentric but offset so it moves fluid. This feeds a piston type pump. This is a variable displacement due to a "swashplate" that changes the piston travel in the bores. 

http://en.wikipedia.org/wiki/Hydraulic_pump

You can see drawings of both pumps on this page. 

When you change engine RPM, but do NOT demand flow from the pump, the swashplate stays perpendicular to the axis of the piston pump. You can spin this pump at any RPM, and it won't pump any fluid while the swashplate is in this position. When you press on the pedal, the swashplate is moved, and the pump moves fluid. 

I'm a bit curious as to why the idle speed lowering. I'll also say that raising the RPM with the throttle stop isn't likely to cause harm to the pump, nor will it make the trans hard to engage in gear. This assumes that the throttle stop is on the engine alone, and not the entire pedal linkage.

doggman · Dec 19, 2007

Re: How many has tried this ~~~~

That kind of explains it. I was curious since it'shydraulicovermechanical and not pure hydraulic (like a skid steer machine). You're right - you should be able to engage the non-synchro trans at any engine speed as long as the existing pedal linkage solely controls the hydraulic motor.You still couldn't disengagethe mechanical system as long as there is any hydro pressure, just as in the normal set up.

KubotaTechnician · Dec 19, 2007

Re: How many has tried this ~~~~

I don't know if any of you have access to the internals of the RTV drive system, but it works like this:

A shaft goes aft from the engine, all the way to the back of the case. It ends about 3-4 inches in front of the filter you see on the back end of the case. This drives the two pumps I described. When you push the pedal, the black casting on top of the case has amechanism in it that varies the swashplate on the pump. The pump feeds the hydraulic motor, which is located just beside the pump. This turns a shaft going forward to the trans, just behind the engine. The trans determines ratio and drive wheels, and sends power back aft via a pinion. In the back case, the axle and differential are located in front of the pumps and in back of the trans, in what equates to a reservoir for the hydraulic fluid.

Ok, so what is the idle lowering device, and why use it?

TWO GUNS · Dec 19, 2007

Re: How many has tried this ~~~~

KUBOTA TECH MAN >>>>>

So what you are saying, if a driver turns his RPM up, let's say 1/4 to 1/2 throttle, shifting will not be a problem.... Will it go in and out of gear the same as if it was idleing ?

Example: Machine is sittling still, in Nuterul, and you turned up the rpm on the engine with the throttle set cable knob on the left, the machine will still go into gear the same as if was just at a idle?

KubotaTechnician · Dec 19, 2007

Re: How many has tried this ~~~~

Assuming theRTV is notmovingAND you have separated the linkage into "throttle" and "pump", you won't be turning the trans.

If the engine RPM is up, it won'tcausethe pump to create flowunless the linkage ALSO calls for the hydraulic system to do so.

What seems to be the key here is the ability to operate the engine RPM independently from the pedal and the hydraulic system control linkage.

The question that occurs to me upon pondering this a bit is:

Letssay that increased RPM leads to more available flow, thus higher pressure to move the RTV. This would allow the RTV to move a larger load from a stop, in theory. 

Ok, so now, lets chain the RTV to a larger load, and leave the engine RPM under control of the pedal. The RTV won't move until pressure builds to a level that will allow the RTV to move with the load. 

Now, add the fact that the throttle stop will not increase top RPM or RTV road speed.

My best guess is that under certain circumstances, you'll see a bit more performance, be it load handling or simply jump "off the line". Otherwise, I'm betting this modification isn't worth too much.

TWO GUNS · Dec 19, 2007

Re: How many has tried this ~~~~

Kubtoa TEch Man >>

The last paragraph, answered all my questions ...

The whole reason for me asking in the begining of this thread, Was so surprised when I found out how to REALLY run the two stage transmission, it opened up a new world of the power I was expecting out of the RTV >>>> Just thought this might be one of them things >>>> I've been very well pleased the way RTV runs. Will keep running it as I have been., and not even going to worry aboutpurchasing and installing the throttle cable. I don't plan on drag racing it anyway.

Ricochet · Dec 20, 2007

Re: How many has tried this ~~~~

[quote user="TWO GUNS"]

Kubtoa TEch Man >>

The last paragraph, answered all my questions ...

The whole reason for me asking in the begining of this thread, Was so surprised when I found out how to REALLY run the two stage transmission, it opened up a new world of the power I was expecting out of the RTV >>>> Just thought this might be one of them things >>>> I've been very well pleased the way RTV runs. Will keep running it as I have been., and not even going to worry aboutpurchasing and installing the throttle cable. I don't plan on drag racing it anyway. [/quote]

I think the mechanic is more or less right, but I wouldn't do it unless your in a tight spot and need more "power". The hand throttle kit links right up to the speed/throttle control lever with the throttle cable from the pedal. So, with the 1 pump 2 motors VHT design and doing this "trick" with the RPM should theoretically help "power" but warranty issues could come into with long term use.

VHT (interesting demo):
http://www.kubota.com/f/products/rtv900/03transmission.cfm#

Also, on the subject of engine governor & vehicle speed. You can release more engine power or RPM by bypassing certain things on the engine, but ultimately your speed is limited by the transmission (gearing...etc.) not HP. Sure, you can get a couple of more MPH with more power, but it ain't much...I would be very surprised if you could hit 30MPH on flat ground. It's not worth the trouble in my book.

TWO GUNS · Dec 20, 2007

Re: How many has tried this ~~~~

Personally, I'm love mine just the way it is >>>> I wouldn't do anything to jeopardizedoing any damage to the machineor it's warranty >>> I would imagine Kubota has their reason for the way everthing is set up from the factory >>>> What folks say anyway, I baby my machine anyway !!!!

 Just the other day, with my GPS, streatched out the RTV on the blacktop in front of the shop, leveled out to a whole 27 mph, that's fast enough, I will probobly never go that fast again in my life,in that machine, for as soon as I found the top end. I shut it back down to 10-12 mph. That's fast enough for me...... Heck, that fast enough for anybody in a RTV !!!!! >>>>. 

 I was running the 27" ITP 589's tires , don't know what it ever done with the stock 25" avt's >>>> never thought about it until questions got brought up alot over the speed of the RTV.

milkman · Dec 20, 2007

Re: How many has tried this ~~~~

On another site, others who don't own/use the RTV, don't think the RTV can do much climbing, mudding, pulling, etc. and there was some reviews posted from ATV magazine that omitted the RTV, maybe a good thing since so many people, including magazine writers don't know how to use the hydrostatic trans. and then would probably declare it a dog like said visitors of the other site. I don't have an RTV yet, but I use my hydro to plow and disc and a lot of people tell me that I have to have a gear tractor to do that kind of work.

TWO GUNS · Dec 20, 2007

Re: How many has tried this ~~~~

Milkman,

I like the way you put it, " Don't have a RTV Yet " >>> sounds good.

Yes, there are some folks that being they don't know, they will dog down other things and other people. That's just the low caliber of people that they are.. I know everybody is happy with their utitltiy vehicles, regardless of what it is. But don't give them the right to judge something that they don't have a clue about. Some of the reasons some of " them " folks do that, is that, they finally realize that they made a big, big mistake by purchasing another make of utiltity vehilce other than the RTV, that didn't do enough researce to find out the " whole " truth. They don't want the world to know that they just got the light bulb turned on in their minds, and it's to late, for they cannot go get another, so they will have to live what's under their butt for now. Or, some of them couldn't afford the quality of the RTV, so they are just going to do what they can, to make people who can afford them, try tofeel bad about their decisions. And then you have some, that no matter what item you have, either theirs are better and for the rest of their life, they hate themselves so much,for the stupid things and wrongdecisions they made at purchasing the equipment that they could or had to get. 

We have had many of utility vehicles on the farms. Many were good, some were better, and we had two that you couldn't give us a semi-truck load of.... And they only stayed on the farm for 7 months, before we lost our butts on them, and got away from them things QUICK !!! But, not going to put down them vehicles, for that was our mistake for getting the things before doing ALL the researce on them. That was a expensive, but great lesson learned. Then came the RTV, in our applications, does serve us the best, so much that withthis nowbeing known, there are plans in the spring to get several more... But also know, that different makes have their different applications, in our case , we work our units, needed something dependable, strong, and something that will last in our line of work... We have no need for speed, so no need for any two seater sport models. But that don't mean they the sport style modelsare no good, just means that in our line of duties., sport models wouldn't serve us as well as heavy duty machines. Tuning the page around, imagine there are many uses for faster, but not as powerful machines, as the sport models, but don't mean that folks has to " Dog " them....

And as far as someone out of the blue, jumping on a RTV and riding it around a dealerships parking lot, so called " test driving " one for several minutes. That's bull ~~ , That won't cut it for the RTV. A person needs to spend some time and learn how the RTV is, & what it is capable of doing. As we all know, it is not like a car or pick-up truck, where one just throws it in gear and go. You have to know and have a little common sense to run the RTV proper. For that is some of the problems with folks who state that they drove one at a dealer, and state that they didn't see what we all see. Either they need to spend some time with someone who knows how the RTV is run, or purchase something else and shut the heck up. 
<DIV> </DIV>

Skipholiday · Dec 27, 2007

Re: How many has tried this ~~~~

Jamie

That has to be the lamest assumption based reply I have everread.

Why are you linking people from another site to this? (mods removed your link)

You don't have a clue how much or how little others know.

Wow some people think they know it all. [*-)]

dkf435 · Dec 27, 2007

Re: How many has tried this ~~~~

Yes it does work. Have the RTV1100 and it comes with a hand throttle. You can pull the throttle cable out and it has a detent to have a higher then normal idle but not full throttle, useful in sumer to keep airconditioner going. You can manually pull it out to get wide open as long as you hold it there. Have used this feature many times to start out on hills while carrying firewood and it works good, you have higher preasure in the pump to work with and you are not at the max on the hydro motor, as speed picks up you just let go and the pedal takes over the throttle and hydro.

Lucky Lady · Dec 28, 2007

Re: How many has tried this ~~~~

Hi, Two Guns, I am a new owner of an RTV900 and have been reading all these posts about dash lights, exterior lights, transmissions, tires, and all the other things...it's a bit mind boggling. We have had our RTV about two weeks now, and it works fine on our farm, but when you mentioned the "Two Stage Tranny" thing I just had to ask about it. Can you point me to the original thread in these posts, so I can find out what you're talking about? I just have to find out what I don't know[:$]

TWO GUNS · Dec 28, 2007

Re: How many has tried this ~~~~



Welcome to the forum !!!

Step into our World .... Happy you got yourself a RTV !!!!

You will Love It ~~~~

***********************************

Ok, giveus a little time, we'll find it...

TWO GUNS · Dec 28, 2007

Re: How many has tried this ~~~~

http://compacttractorreview.com/cs/forums/thread/8066.aspx



This is one of them ~~~ I know there are several !!!!

How many has tried this ~~~~

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