Heizohack HM8-400

[aodhagan]

Hi everybody. I have a Heizohack hm8-400 chipper and I'm very happy with it. It can run up to a max speed of 750rpm but I've only ever ran it at about 580rpm. I'd like to know if anybody has any experience of running one of these chippers on the 1000rpm shaft ? Any advice would be appreciated.. Thanks

[Tom D]

No need to change the shaft, just run it in 1000 gear and match the revs, you can go to 800 ok. I think it runs better at 750 than 540..

[aodhagan]

Thanks for the reply Tom.. The reason I ask is because there's a 180hp tractor for sale beside me and I'd be interested in it but it's only got a 1000 shaft, it can't be swapped over to a 540.. I've never run my chipper at more than about 600 revs, have you run yours at 800 ? Thanks

[Tom D]

I always run mine at 800.

 

180 hp is about ideal for the 8-400, you'll go through a few shear pins, but thats what they are for...

 

I had mine on a 210hp new holland on one job, it would do about 100 ton a day.

[aodhagan]

that's great Tom, it's great to hear from someone who has ran the chipper at 800.. I was afraid to being honest ! I'm going to have a look at this tractor tomorrow and now I can look at it without worrying about whether it'll drive the chipper or not.. Cheers.

[renewablejohn]

Was told to always run my Heizohack no more than 10% less than max speed therefore have always used it on the 1000 pto shaft.

[aodhagan]

For some reason I've been afraid to run mine at more than 600.. I Have it about 12 months and have only chipped about 200t in that time but I'm starting a 2nd supply contract on Wednesday this week and that'll take me up to approx 60t per month... after reading this from you lads I'll be running her at 800 for sure.. She's had her settling in time, now it's time to earn her keep.. Many thanks lads

[cornish wood burner]

For some reason I've been afraid to run mine at more than 600.. I Have it about 12 months and have only chipped about 200t in that time but I'm starting a 2nd supply contract on Wednesday this week and that'll take me up to approx 60t per month... after reading this from you lads I'll be running her at 800 for sure.. She's had her settling in time, now it's time to earn her keep.. Many thanks lads

 

If your machine is designed to run at 750rpm I would keep to that. 800 rpm is only 6% over max rpm but you will be increasing the stress by almost 14%.

[renewablejohn]

If your machine is designed to run at 750rpm I would keep to that. 800 rpm is only 6% over max rpm but you will be increasing the stress by almost 14%.

 

The 10% I referred to is the lower figure on the speed range so 750 would be highest speed and 675 min speed. I normally run 725 min and 750 max.

[cornish wood burner]

The 10% I referred to is the lower figure on the speed range so 750 would be highest speed and 675 min speed. I normally run 725 min and 750 max.

 

Exactly. Stress increases by the square of the speed so a little over speed can result in a bigger increase in stress of the rotating parts. I'm sure manufactures will have built in a considerable safety margin but 800rpm is eating into it.