Questions about New Holland 451 Mower

[Rivendale]

Hi Folks,

I just picked up a nice 451 at an auction last weekend. I had been reading up on it and also got a crash course from the farmer I bought it from. I got it hooked up and running with no problem.

It has the combine style guards on it (doubles with no ledger plates) I am curious about the operating PTO speed. I own an oliver sickle mower with a pitman and I know it was actually a detriment to run it anywhere near 540. I assume this is true also with the belt driven 451?

Whats the rule of thumb? I know you want to run ground speed fast enough so that the forage "topples" back over the bar...but I assume it isnt good to run it at 540?

Also anybody want to offer any tips or useful information about running a 451 to a newbie?

Thanks in advance

 

[mjcountrybumpkin]

We have 2 451 mowers and they are always run at 540,never had any problems. I have found with the mower hooked up and flat on the ground I personally adjust the cutter bar were the outer end leads the inside by a couple of inches( so when you are mowing the drag of the hay pulls the bar back to being straight in line). I do this by adjusting the top link. I personally love to mow with outs, more so than with the new 8' Kuhn disc mower.

Best of luck
Make sure to religiously grease the wobblers !

 

[mjcountrybumpkin]

P.S.

The faster you can mow (ground speed) the easier it will be to keep it from clogging up.

 

[Rivendale]

We have 2 451 mowers and they are always run at 540,never had any problems. I have found with the mower hooked up and flat on the ground I personally adjust the cutter bar were the outer end leads the inside by a couple of inches( so when you are mowing the drag of the hay pulls the bar back to being straight in line). I do this by adjusting the top link. I personally love to mow with outs, more so than with the new 8' Kuhn disc mower.

Best of luck
Make sure to religiously grease the wobblers !

Good tips. I am going to run it on my Deere 2030. One thing I hate about it is that it doesn't have stabilizer brackets... No way to attach a stablizer...so I hear ya about adjusting the end forward a bit but I wont do me any good with the 2030. Maybe after I get my Massey 135 put back together it can be my mowing and raking tractor and let the 2030 do all the baling only.

 

[dlrfarms]

NH 451 has built in stabilizer system. u shaped and fastens to the toplink

 

[crowbar032]

You want to run at 540. Make sure that you have the double knife on the end, it will mow much better and clog less. And as posted above, grease often and liberally.

 

[mjcountrybumpkin]

depending on what type of toplink you have you may have to get a universal toplink to use with the 451.I was reminded of that today while hooking mine up.as was said earlier no stabilzer needed just hook and go.a neat little side trick,if you are mowing down bushes or light brush you can make an initial pass with pto on to cut material and then back up and turn off pto lay barn down like you were going to mow and drive forward.it will rake up brush in a pile rather nice.just be careful not to over do it raking to much weight or it will trip.that brings up another point,liberal with grease every where except the trip mechanism unless you like backing up a LOT to reset it.Hope it is working well for you.there are some very well hidden grease fittings on the 3 pt. assembly you need to look from underneath while laying on your back to see.we have had 451s my whole life and i found a fitting no one else knew was there last year.

 

[sweettractors]

NH 451 has built in stabilizer system. u shaped and fastens to the toplink

Exactly right. Ken Sweet

 

[petes]

The PTO driven pulley sheave has an adjustable diameter, so you may need to add/remove shims or flip the outer (rear) half over to get the right ratio. Spec is 800rpm sickle crank speed. The adjustable pulley allows for a range from 540 to 720 RPM PTO.
PM me if you want a PDF of the users manual. It's quite helpful in getting it set up correctly.

 

[Rivendale]

Thank you everyone for the great feedback. I mowed about 8 acres of hay this afternoon and it did wonderfully even in the gross thick hay. I want to put more down but I am gambling with the rain...

 

[davel8257]

I just bought a used 451 mower this weekend. I put it on the tractor and in 10 minutes was out doing some light mowing (weeds, road side grass). The sickle bar seemed to be set pretty high, so I thought I'd try to adjust it downward. The former owner said some things about the 2 arms that have slip fittings -- get them set and the heighth will be perfect.

Ok -- so, I undid the (2) 3/4" nuts and bolts on both sides, tripped the latch and tried some adjustments. I moved it way up -- the bar seemed at even steep (more upright) angle. So, I moved the grippers down on the arms back to about where they were. Now, I have a new problem...

On my Kioti, the stabilizers are attached with an eyebolt which is held in place with a large nut on the inside of the 3pt arm. That nut hits the gripper assembly on the mower. If I get one side on, I can't get the other side on - the nut hits the side of the gripper assembly. It's dark now (been working on for 2 hours!) -- I could try to post some pics tomorrow evening after work.

And with all of this up/down, jiggle that, move there. bang on this thingy ... it seems to me that I should have chosen an entirely different approach to setting the angle of the sickle bar. There's a couple lengthes of chain on the sickle bar attached to a threaded eye-bolt. If I unscrewed (lengthened) the eyebolt, my guess is that the sickle bar would lay down flatter.

Signed,
take 2 aspirin and maybe the banging in my head will stop...

 

[sweettractors]

I just bought a used 451 mower this weekend. I put it on the tractor and in 10 minutes was out doing some light mowing (weeds, road side grass). The sickle bar seemed to be set pretty high, so I thought I'd try to adjust it downward. The former owner said some things about the 2 arms that have slip fittings -- get them set and the heighth will be perfect.

Ok -- so, I undid the (2) 3/4" nuts and bolts on both sides, tripped the latch and tried some adjustments. I moved it way up -- the bar seemed at even steep (more upright) angle. So, I moved the grippers down on the arms back to about where they were. Now, I have a new problem...

On my Kioti, the stabilizers are attached with an eyebolt which is held in place with a large nut on the inside of the 3pt arm. That nut hits the gripper assembly on the mower. If I get one side on, I can't get the other side on - the nut hits the side of the gripper assembly. It's dark now (been working on for 2 hours!) -- I could try to post some pics tomorrow evening after work.

And with all of this up/down, jiggle that, move there. bang on this thingy ... it seems to me that I should have chosen an entirely different approach to setting the angle of the sickle bar. There's a couple lengthes of chain on the sickle bar attached to a threaded eye-bolt. If I unscrewed (lengthened) the eyebolt, my guess is that the sickle bar would lay down flatter.

Signed,
take 2 aspirin and maybe the banging in my head will stop...

Try putting mower back where you were not having a problem......To adjust the height you carry the mower on your 3 point lift arms, set the depth control on your tractor.......control blade angle with toplink. Ken Sweet

 

[davel8257]

I'm not 100% sure I remember where it was set initially -- that's what occured to me as I walked back into the house tonight...

I can see how the angle would be affected by the top-link. I played with that a bit.

The other 2 points that you suggest are intuitively likely, but not consistent with my real-life experience.

For instance, when I lowered the arms all the way down -- the 'runners' on the bottom of the mower were still off of the ground. It seems that the 'grippers' were holding onto the slip arms and keeping them 'up'. Thus, lowering my 3pt arms did not let the sickle bar fully settle onto the ground resulting in a higher cut than I wanted.

I'm not sure what you mean by 'depth control' on my tractor? I have the arms set in the lowest notch of the lift-arms -- this should allow my arms to get just about as low to the ground as possible.

I had a random thought about the stabilizer attachment. If I removed the stabilizer eyebolt and nut -- I'd not have a problem. If I used that eyebolt and nut and ran it through the lift-arm attachment, I'd also not have an interference problem. (I might have other problems -- like a stabilizer link that is too long and would need to be shortened to be useful.).

 

[sweettractors]

I'm not 100% sure I remember where it was set initially -- that's what occured to me as I walked back into the house tonight...

I can see how the angle would be affected by the top-link. I played with that a bit.

The other 2 points that you suggest are intuitively likely, but not consistent with my real-life experience.

For instance, when I lowered the arms all the way down -- the 'runners' on the bottom of the mower were still off of the ground. It seems that the 'grippers' were holding onto the slip arms and keeping them 'up'. Thus, lowering my 3pt arms did not let the sickle bar fully settle onto the ground resulting in a higher cut than I wanted.

I'm not sure what you mean by 'depth control' on my tractor? I have the arms set in the lowest notch of the lift-arms -- this should allow my arms to get just about as low to the ground as possible.

I had a random thought about the stabilizer attachment. If I removed the stabilizer eyebolt and nut -- I'd not have a problem. If I used that eyebolt and nut and ran it through the lift-arm attachment, I'd also not have an interference problem. (I might have other problems -- like a stabilizer link that is too long and would need to be shortened to be useful.).

Making the toplink longer raises the tips of the rock guards. If you need more....look behind the big drive pully and you will see grooves and a clamp plate.... adjust more angle here. Are you calling the sickle bar inside and outside skid shoes runners or are you referring to the 2 3/4" diameter stands under the a-frame?.....Don't try to tightly stabilize the mowers left right swing unless it is getting into your tires.....a owners manual would be very beneficial.....lots of them on ebay cheap. Ken Sweet

 

[davel8257]

Fortunately, I took a picture of the mower when I brought it home. I was able to count the notches on the arms and re-set the configuration back to the way it was when I got it. I had to line up the mower exactly centered behind the tractor and got it re-connected to the tractor.

I then drove away and began to hear 'strange' noises from the tractor. I had raised the arms to drive away. But, the top-link structure on the 451 was being forced up against the hook up on the tractor. It was only being allowed to raise a couple of inches. That was not sufficient for the drive pulley (at the hinge) to clear the ground. It was dragging in the grass.

So, I 'fixed' one issue (barely -- stabilizer arm nut barely clears the grippers on the 451), but created a new one (very limited vertical lift range).

I've taken the 451 off and moved onto another project. I'll get back to this in a few weeks when the grass grows back up and I need to do more mowing.

 

[Haydog]

Hi I'm new to the forum. I saw that someone may have a pdf for a NH 451. I just bought one and was looking for a manual.

 

[petes]

The levers and eyebolts on the U shaped stabilizer are used to switch between hook-up and mowing modes.
If the eyebolts are unhooked the mower frame can be lowered all the way to the ground (set on the 3/4" diameter parking skids) to be unhooked from the 3pt. After hooking up, raise the 3pt and engage the eyebolts/levers for transport and mowing. The mower frame will (should) be stopped at the correct height when lowered, allowing the cable to lower the cutterbar to the ground for mowing but keeping the mower frame off the ground. When everything is set correctly, the top of the rectangular horizontal tube of the frame should be 16" off the ground when lowered (eyebolts hooked). Adjust the position of the cone shaped stops on the U shaped stabilizer to get it at 16". When eyebolts are hooked and the 3pt is lifted adn lowered, the cable/spring causes the cutterbar to lift and lower while remaining parallel to the ground, (the mower frame stays at the same height), enabling it to clear obstructions or already downed grass.

 

[petes]

The levers and eyebolts on the U shaped stabilizer are used to switch between hook-up and mowing modes.
If the eyebolts are unhooked the mower frame can be lowered all the way to the ground (set on the 3/4" diameter parking skids) to be unhooked from the 3pt. After hooking up, raise the 3pt and engage the eyebolts/levers for transport and mowing. The mower frame will (should) be stopped at the correct height when lowered, allowing the cable to lower the cutterbar to the ground for mowing but keeping the mower frame off the ground. When everything is set correctly, the top of the rectangular horizontal tube of the frame should be 16" off the ground when lowered (eyebolts hooked). Adjust the position of the cone shaped stops on the U shaped stabilizer to get it at 16". When eyebolts are hooked and the 3pt is lifted adn lowered, the cable/spring causes the cutterbar to lift and lower while remaining parallel to the ground, (the mower frame stays at the same height), enabling it to clear obstructions or already downed grass.

 

[keegs]

Try putting mower back where you were not having a problem......To adjust the height you carry the mower on your 3 point lift arms, set the depth control on your tractor.......control blade angle with toplink. Ken Sweet

+1 ....

 

[BaiJiu]

Hi I'm new to the forum. I saw that someone may have a pdf for a NH 451. I just bought one and was looking for a manual.

Did you ever find a manual? I bought a NH 451 this week and can't seem to find a manual at a reasonable price. There are a few in the US but with the CDN dollar being so low, shipping and tax they are nearly $100 just too expensive for me.