Mowing Mowing with HST

[ScottL]

I finally got my mower (Land Pride finish mower) hooked up and ready to mow on my 1996 B7100HST yesterday.

According to the mower manual, I needed to mow with the PTO in low, since a 540RPM speed at the PTO was necessary. OK. Here are the questions.

1) There is no tach on my tractor. Does anyone have a feel for the approximate throttle opening on a B7100HST for 540RPM? The mower book specifically said not to run full throttle, but I'm sure this is a CYA on their part. How do they know what my tractor PTO RPM is at any given throttle?

2) If I mowed with the tractor gearbox (not PTO, tractor) in low range, I had to use almost full throttle to maintain any kind of speed. If I mowed with the gearbox in high range, I had two choices: run about 40% throttle with my foot all the way on the drive pedal (didn't cut too well, because the blades weren't turning fast enough), or run 75% throttle and 'feather' the drive pedal to maintain a low speed. Here is the question: I keep thinking of the drive pedal as a clutch, and I keep thinking that riding the drive pedal for long periods like that is going to burn something out. Please assure me the tractor is made to run forever with the drive pedal halfway down, or I'm going to have a tough time mowing with this rig. Is it OK?

 

[HR_Mutt]

ScottL
I always mow in high range w/ HST and throttle wiiide open. The woods mower doesn't seem to mind a bit. Just do the preventitive maintenance on it. Use the accelerator pedal depending on how deep the grass is, watch the discharge at different speeds, you'll find the best speed for your lawn. As far as the pedal halfway... that's the beauty of HST/w3tcompact/icons/smile.gif.
regards
Mutt

 

[Bird]

Scott, on the B7100 (and some other Kubotas without a tach), the 540 PTO speed is accomplished by opening full throttle, then ease off just a little bit (and that's the way the dealers usually tell customers to do it). PTO speed is only a couple hundred RPM below full throttle.

And for the mower to cut properly, you probably need that PTO RPM. I wouldn't worry about not having the pedal all the way down. If having the pedal all the way down in low range is fast enough to suit you, then do that, but if that's too slow, use the high range unless it sounds like the engine's laboring.

Bird

 

[frank_f15]

scott: bird nailed it perfectly. full then back off just a bit. the beautly of hst is set the rpm and use the forward pedal for your speed. u can go flat out or just creep, rpms stay the same.

 

[Kelvin]

I know that the conventional wisdom for the B7100 (which has no Tach) is to go full throttle and back off a bit. I will add this bit of information, however:

I installed a temperature guage on my older B7100. I have found that the engine runs about 20 degrees cooler at full throttle than it does at "slightly less than full throttle" when mowing.

Overall I will agree with everyone else: Use either full throttle or nearly full throttle and then use either high or low range as your mowing conditions and terrain slope dictate. I see no problem creeping along in high-range if you want or need to do that.

Hope this helps,
Kelvin

 

[bpence]

I have a 95 B7100 and usually mow with the transmission in hi-range and the throttle wide open. No problems is you decide to back off full throttle just a bit. With the B7100 you'll learn over time that a lot of things are "more art than science". You need to run at near full/full throttle to get enough power to the mower so it can do it's job properly. Try a couple of different throttle settings and determine what works best and what you like. I also recommend ear plugs or muffs. That little diesel with a mower whine can get pretty loud pretty quickly.

Bob Pence

 

[RPM]

I wouldn't worry about the load on the HST when just pulling along a mower or rotary cutter. Don't think of it as a clutch (with plates slipping and all the other good stuff). Your tractor's HST is designed to take the abuse of pulling implements like a box-blade, back-blade etc.

The major issue you want to watch out for with a HST is trying to pull an immoveable load. If you do this then you could pop a few hydraulic seals. Hopefully there's some kind of relief valve on the Kubotas to avoid this - it's messy whichever way it happens in my experience. If you did this with a standard transmission you'd just stall the engine. Luckily most Kubotas are light enough and the engines have enough torque that you are more likely to spin all four wheels in 4wd ... have done this a few times on my BX already although it's not really a good idea /w3tcompact/icons/crazy.gif.

As for the PTO - what you want to watch out for when running an implement off the PTO is how you engage it. I was always told to engage the PTO at low engine RPM and then open up the throttle - avoids shock loading the PTO drive-line.

 

[ScottL]

Thanks to all the people who replied. What a great resource this web site has become!

I already figured out that I need earplugs when mowing. Man, what a racket!

The tractor chugs right along as long as I keep the throttle high enough through the deeper stuff. I ended up running high range and feathering the pedal to keep it at the right speed.

Thanks to everyone.