Rough start-up for RFM

RickS · Apr 19, 2006

I attached my new 5' KK RFM last evening to my JD 4010. When I got everything on and hooked up I engaged the PTO at about 1500 rpm. The whole thing shook and killed the tractor. I tried again at 2000 rpm and again the entire vehicle shook but the tractor kept running, although it did bog down a little until the mower started turning. Is this fairly normal for a FM? It had been sitting on the lot at TSC for at least six months, and from the looks of it maybe close to a year. Could it just need running to help the belt flex easier? Once cranked up to 2900 rpm/540 PTO rpm it was smooth and mostly vibration free. I didn't cut with it, just let it spin in the air.

bjr · Apr 19, 2006

Acronyms and abbreviation here are confusing. I gotta know what's a RFM? bjr

RonR · Apr 19, 2006

Rick,

I'd loosen the belt to see if the spindles turn freely. A mower shouldn't hang up if there's not an obstruction. I'd also check the gear oil (if it has that) and/or grease it well.

A stiff belt shouldn't cause that I don't think. With the belt loose or off, the spindles should spin easily. If not, I'd take it back. Or insist on new spindles and more discount.

If it doesn't rotate freely on its own, I'd be concerned that it might have rusted bearings..................

Rear Finish Mower.

ron

MrJimi · Apr 19, 2006

( Acronyms and abbreviation here are confusing. I gotta know what's a RFM? bjr )

Just being a newbie here? I would suggest
RFM=rotary field mower?
Jim /forums/images/graemlins/smile.gif

sweettractors · Apr 19, 2006

I would suggest starting at a lower rpm and after it starts turning, increase speed from there--Ken Sweet

Sweet Farm Equipment LLC *New 4-5-6-7 Ft First Choice Finish Mowers in stock today*

Jagmandave · Apr 19, 2006

RFM = rear finish mower, I think...........

When I used to start up my bush hog, it took the rpm down a bit till it came up to speed, but this doesn't sound right for a tractor powered unit unless it's a really big one!

Soundguy · Apr 19, 2006

( I engaged the PTO at about 1500 rpm. The whole thing shook and killed the tractor. I tried again at 2000 rpm and again the entire vehicle shook )

Wow.. I engage my mowers at about 1000 rpm.. that includes my big 10' mower. I'd be a tad shy at engaging at a higher rpm.

I think you may have had a sticky spindle, if it loaded the tractor down at 1500 rpm and stalled it.. That would be a cause for concern.. having to tach up to 2000 rpm to get my mower spinning. If this mower was way oversized for the tractor, I could see that situation.. Like runing a 5' brush mower on an 16 pto hp machine.. etc.

Soundguy

RickS · Apr 19, 2006

Thanks for the replies. RFM is Rear Finish Mower. It is 5' with three blades. My PTO is 14 hp. I'll check the spindles. I was able to turn the blades by hand when I was attatching the PTO shaft, so I don't think they are too rusted.

sweettractors · Apr 19, 2006

Rick, Be sure to engage the RFM, when the mower is not in the grass?? (not loaded)--Ken Sweet

RickS · Apr 19, 2006

( Rick, Be sure to engage the RFM, when the mower is not in the grass?? (not loaded)--Ken Sweet )

Roger that, Ken. I engage it while raised on the 3pt hitch.

wushaw · Apr 19, 2006

I had a different brand RFM that was smooth and vibration free at any rpm setting from idel to mowin speed.
I thing you have something out of ballance or what has been said about a bad spindel. I ran this mower behind a tractor that had 15hp at the pto.

Fishguy · Apr 19, 2006

I "assume" you filled the gearbox with oil lubed all the spindles first, right? /forums/images/graemlins/blush.gif I recently bought one from TSC as well (6') and they are not serviced.
Also, remove the belt cover and see if the owners manual is under there. Don't know why they put them there, but mine was trashed by rain and the initial run up. Sure made a wierd noise. /forums/images/graemlins/wink.gif
Luckily I had printed on off their web site prior and found what needed to be done before use.

Good luck!
Steve

RickS · Apr 19, 2006

Yes, I filled the gearbox and found the manual, albeit by accident. Strange place to put it. /forums/images/graemlins/tongue.gif I greased everything, but I'll check closer this evening. Thanks for the replies.

KiotiJohn · Apr 19, 2006

Best to start your mower barely lifted, not too high, or not lifted at all but sitting on the wheels. Safety first. If the blades were loose or there was something caught up underneath, you'd stand a better chance of not doing any damage with the mower down low.

The first thing that I thought of was, is the PTO shaft hitting/rubbing on something since you have the mower lifted. If the shaft wasn't cut just right, it could bind on lifting. Make sure you check where it's positioned when fully raised.
John

George2615 · Apr 19, 2006

I just bought the 5' KK rotary cutter (2 blade). Assembled it, filled gearbox, greased u-joints, then hooked it up and took it out to the driveway to test run. I engaged it at a low RPM (owners manual says to engage at idle) and it seemed to be off balance (quite a bit of vibration). Stopped the tractor and checked underneath for any looseness or a bent blade or something but found nothing bad or bent. Blades have about 3/8 - 1/2" play lifting up on the end of the blade. Blade mount bolts are tight. They have to be free to pivot if you hit something solid just seems to me like more up /down play than I'd like to see. Vibration eased up a little at 540 RPM. Maybe I'm just not used to the shaking. Those 2 blades have a lot of weight to spin around. Maybe they aren't balanced blades?

KiotiJohn · Apr 19, 2006

( They have to be free to pivot if you hit something solid just seems to me like more up /down play than I'd like to see. Vibration eased up a little at 540 RPM. Maybe I'm just not used to the shaking. Those 2 blades have a lot of weight to spin around. Maybe they aren't balanced blades? )
I don't have a lot of up/down play in my RC, but I want to suggest that what happened may be that one of your blades didn't spin out as fast as the other, getting the vibration started and then the other kicked out, but the vibration already had its momentum.

When that happens, try lowering the RPM back down and letting it settle a bit and then run it back up, or disengage the PTO and let it spin down and restart it at low idle again.

I've had it happen several times on mine after some materials got wrapped around one blade making it start the throw out a little later than the other blade. One that has sat outside at the store for a while may just have had enough rust to cause the same problem. Spray the mounting side of each blade with Lithium delayed viscosity grease and it should help.
John

gator · Apr 19, 2006

( Roger that, Ken. I engage it while raised on the 3pt hitch. )

Rick did you check the PTO length to make sure its not to long and bound up when you start it with the 3PH up? Just a thought.

H3hound · Apr 19, 2006

I just got the 72" 3 spindle KK finish mower. I do not engage in the raised position and start at or just below 1000RPM. Mine spins up smoothly. Also, I did not have to cut the PTO shaft to fit.

I would check for free movement in all the moving parts, make sure the blades are on correctly - one could be upsidedown, and recheck the PTO connections - shear bolt, PTO/tractor clip, PTO size.

Good luck.

john_bud · Apr 19, 2006

Rick,

Do you put in the clutch when you engage the PTO and then slowly let out the clutch? The shock load from just flipping the switch will either wear out PTO clutches (if you have them) or snap something inside the tractor making loud expensive sounds.

Also, does it have a shear bolt of slip clutch on the PTO driveline? If it has a slip clutch, you need to loosen it up, allow it to slip, then tighten it back down to specs. Slip clutches have a tendency to rust up and not slip making that expensive noise when a large rock, stump or what not is pinned by a blade.

luck!

jb

RickS · Apr 19, 2006

( Rick,

Do you put in the clutch when you engage the PTO and then slowly let out the clutch? The shock load from just flipping the switch will either wear out PTO clutches (if you have them) or snap something inside the tractor making loud expensive sounds.

Also, does it have a shear bolt of slip clutch on the PTO driveline? If it has a slip clutch, you need to loosen it up, allow it to slip, then tighten it back down to specs. Slip clutches have a tendency to rust up and not slip making that expensive noise when a large rock, stump or what not is pinned by a blade.

luck!

jb )

jb, my 4010 does not have a clutch, just a PTO on/off knob. It is full hydrostatic. With my tiller it sort of "soft starts". I can engage the PTO at idle with no problem. I will look closer at the mower soon. Just not enough time in the day.

The mower came with shear bolt. I would like to get a slip clutch for it, but I'm actually considering selling the whole thing and getting a riding mower, so I'll hold off for now. I don't really need the tractor now that I've done my tilling and dirt work. We'll see. Thanks for the reply.