Part set of knives in a forager

[mf7480]

I’ve been looking for a used self propelled, a John Deere 7450 has come up that is just about perfect, right price, immaculate, low hours.

Only trouble is it’s got a 56 blade cylinder instead of the conventional 40 blade. I wouldn’t want the short chop length the AD men require, but am told and there’s John Deere literature showing they can be run with a 3/4 or 1/2 set of knives.

My question is will a 56 blade cylinder with a 3/4 set of knives (42) run as well as a 40 blade cylinder with a full set?

Will it use more power and will it run as smooth as having a proper 40 knife cylinder?

Best regards

 

[e3120]

My thinking would be that a 3/4 set won't give a even chop length. 75% will be just as short with the rest twice as long. Maybe this will never be seen.

Would there be enough scope to set the feed roller speed to give your desired chop length with either a full or half set?

 

[davidroberts30]

Half set and change the feed roller gears to suit your chop length

 

[mf7480]

I think you’re right in what you’re saying- with a 3/4 set the chop length will be all over the place. With a full set the chop length is hydraulically variable from 4mm- 19mm, so a half set giving 8-38mm will be about right. 25mm will be right in the middle of the feed roll operating range.

Only question that remains is whether the ‘unused’ blade carriers get in the way and sap power?

 

[davidroberts30]

I think you’re right in what you’re saying- with a 3/4 set the chop length will be all over the place. With a full set the chop length is hydraulically variable from 4mm- 19mm, so a half set giving 8-38mm will be about right. 25mm will be right in the middle of the feed roll operating range.

Only question that remains is whether the ‘unused’ blade carriers get in the way and sap power?

never used to on the old nh1905 here

 

[davidroberts30]

I think you’re right in what you’re saying- with a 3/4 set the chop length will be all over the place. With a full set the chop length is hydraulically variable from 4mm- 19mm, so a half set giving 8-38mm will be about right. 25mm will be right in the middle of the feed roll operating range.

Only question that remains is whether the ‘unused’ blade carriers get in the way and sap power?

with a 3/4 set you probably move the carriers so the blades are even distance apart

 

[sawdust]

with a 3/4 set you probably move the carriers so the blades are even distance apart

You’d need to, would you not, to maintain balance?

 

[mf7480]

You’d need to, would you not, to maintain balance?

I don’t think so. John Deere knives are in a strange arrangement, they’re all staggered. With a 3/4 set you take out specific knives from a diagram.

 

[davidroberts30]

as long as each blade has a opposite

 

[fermerboy]

The spare carriers would be keeping weight in the drum to help with momentum I would have tbought.

 

[Chae1]

Was reading in harvestimes the claas magazine that they now have a feature that doesn't chop it as short. Think it was called shredlage.

Our contractor had a similar feature, by the end of the day his blades were so blunt the chopper was on its knees and going at half the speed.

 

[Al R]

Was reading in harvestimes the claas magazine that they now have a feature that doesn't chop it as short. Think it was called shredlage.

Our contractor had a similar feature, by the end of the day his blades were so blunt the chopper was on its knees and going at half the speed.

I put “half blades” in a Jag once, all 20 were fitted but they only had half a blade, meant for longer chop, what a nightmare, I didn’t do 10 acre before I swapped back to full length blades and ran on the longest chop setting.

With the JD’s, look in the manual (you can get them online) and it tells you which ones to take out. 7450’s are lovely harvesters that can certainly shift when set up right.

 

[Jon Boy]

All our JD choppers have 48 knife drums , for grass we always run a half set and whole crop and maize we run a full set you wont notice any difference in power consumption with a half set they run the same as a full set they dont block they dont run rough . We havnt run 3/4 set before but i dont see you having any problems you wont notice any variation in chop lentgh in grass and will be hard pushed to find it in maize.

 

[Speedstar]

Years ago we ran a half set in two demo foragers and they would not go well at all , why not run a full set ?

 

[mf7480]

Years ago we ran a half set in two demo foragers and they would not go well at all , why not run a full set ?

Only because we don’t want the grass cut to 19mm, which is the longest it can chop with that cylinder

 

[mf7480]

Years ago we ran a half set in two demo foragers and they would not go well at all , why not run a full set ?

Were they John Deere?

 

[Speedstar]

Were they John Deere?

Yes one was a John Deere,years ago had a trailed John Deere and tried to run a half set of blades in it and it took a lot more power to run it,would you not be better to have a bio gas drum and a standard drum for it to do both jobs right ?

 

[benferg]

Know of several claas foragers that run half knives in grass and wholecrop.

No complaints from the operator or the farmers