Harman stoker expert?

Harman stoker expert?

PostBy: coalkirk On: Sat Jul 26, 2008 8:23 am

Anyone here who is intimatley familiar with all the parts and pieces of the Harman stoker mechanism? Before last season, i disassembled my stoker unit and cleaned and lubricated everything. When i was finsihed and had reassembled, yea I had a part left over. Shouldn't drink beer during these maintenance sessions. Anyway the unit worked fine. This year, I'm experementing with buckwheat coal in the unit. I test fired last night and it didn't wotk too swell. I couldn't push enough coal to cover the grate. I adjusted the feed to max but it stillisn't pushing enough. The pusher block indicator only comes back to the fourth dot and when it pushes, it doesn't quite go all the way tothe first dot. I think my "left over part" may be the cause. It's a spacer or bushing. It's inside diameter is too small to fit over the threaded pusher rod. I'm stumped and need some help. Here's a pic of the little bugger. The parts diagram in the manual might as well be drawn with a crayon.
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coalkirk
 
Stoker Coal Boiler: Harman VF3000
Coal Size/Type: antrhcite/rice coal

Re: Harman stoker expert?

PostBy: Wood'nCoal On: Sat Jul 26, 2008 8:26 am

I hate when I have parts left over. :mad:
Wood'nCoal
 
Stoker Coal Boiler: 1959 EFM 350
Hand Fed Coal Stove: Harman Magnafire Mark I
Coal Size/Type: Rice and Chestnut
Other Heating: Fisher Fireplace Insert

Re: Harman stoker expert?

PostBy: Steve.N On: Sat Jul 26, 2008 8:38 am

I am pretty sure it is part #21 on the exploded view in the manual. Cam pusher bearing. If not let me know and I will contace Harman dealer tech service on Monday
Steve.N
 
Stove/Furnace Make: Harman mkII
Stove/Furnace Model: Axeman Anderson 260 at store

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Re: Harman stoker expert?

PostBy: Bulldogr6 On: Sat Jul 26, 2008 2:10 pm

^^


I agree with Steve. I went down and looked mine over cause the hopper is off it looks like that is the only thing it could be.
Bulldogr6
 
Hot Air Coal Stoker Stove: Harmon Magnum
Baseburners & Antiques: Station Agent 24
Coal Size/Type: Rice & Nut

Re: Harman stoker expert?

PostBy: coalkirk On: Sat Jul 26, 2008 3:14 pm

Well I got all excited when I read your responses but unfortunatley, that's not it. I should have put something in the pic to give it perspective. The cam bearing is much larger, about the diameter of a quarter. This part is much smaller. Here's another pic with a quarter for size perspective. I'd really appreciate it if you could talk to Harman tech suport for me on Monday Steve. I've got a 24 ton of coal coming this week and i was hoping to use buck. If I can't get the pusher to move a larger amount of coal, I've got to go with rice. When the pusher is moving back and forth, after it stops, i can grab the rod with my hand and move it back further and more coal drops in. if it could move like that by itself, the buck would work. Again, I'd appreciate any help. Thanks
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coalkirk
 
Stoker Coal Boiler: Harman VF3000
Coal Size/Type: antrhcite/rice coal

Re: Harman stoker expert?

PostBy: coalkirk On: Sat Jul 26, 2008 3:49 pm

OK, cancel the APB on this part. I figured out what it is and where it goes. It goes behind the feed indicator. It rides in the channel between the pusher block and the indicator. It not being there may be causing the pusher block to hang up alittle and limiting its travel. I'm still reassmebling the stoker. Will test and post results later. Thanks all. :oops: :cheers:
coalkirk
 
Stoker Coal Boiler: Harman VF3000
Coal Size/Type: antrhcite/rice coal

Re: Harman stoker expert?

PostBy: Steve.N On: Sat Jul 26, 2008 3:58 pm

Good find. I am still going to talk to Harman and see if there is a better detailed parts breakdown available I will let you Monday
Steve.N
 
Stove/Furnace Make: Harman mkII
Stove/Furnace Model: Axeman Anderson 260 at store

Re: Harman stoker expert?

PostBy: CapeCoaler On: Sat Jul 26, 2008 4:07 pm

Young Frankenstein- "Parts is Parts"
CapeCoaler
 
Stoker Coal Boiler: want AA130
Hand Fed Coal Stove: DS Machine BS#4, Harman MKII, Hitzer 503,...
Coal Size/Type: Pea/Nut/Stove

Re: Harman stoker expert?

PostBy: coalkirk On: Sat Jul 26, 2008 5:12 pm

Well the saga continues. Everything is back together, cleaned and lubricated. However, I still can't adjust the feed rate as much as I'd like. When the pusher block is in the retreat position, it only will go to the fourth hole on the indicator. (see photo A) When it pushes, it only goes to the second hole. (See photo B) I can take my hand while it's cycling and make it come all the way back to the sixth hole and when it pushes, I can make it go to the the first hole. If it would do that on it's own, the buckwheat coal would work. As it is last night when I test fired it, I could only get fire on the first 1/3 of the grate. not enough to do the job. With rice coal, you could push live coal off of the grate into the ash pan if you wanted to. Of course you wouldn't want to. Anyone with a harman stoker, can you test the stoker stroke when adjusted all the way too max and see how yours behaves? Any other ideas?
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coalkirk
 
Stoker Coal Boiler: Harman VF3000
Coal Size/Type: antrhcite/rice coal

Re: Harman stoker expert?

PostBy: Highlander On: Sat Jul 26, 2008 6:44 pm

Kirk, did the stroke adjustment change somehow? I never liked the way these stokers set the stroke, using a wingnut to lock the adjustment handle at a particular position. I have found that the amount of engagement of the 1/4" threaded rod into the pusher block is not real precise. If you didn't thread it in as deeply as it was before, you just increased the gap between the collar and the block, reducing your stroke.

I modified my stoker by using a shim inbetween the pusher block and the collar that rides on top of the threaded rod. The shim is nothing more than a brass nut that I've sanded down till its just the ritght thickness, about 1/8". It lets me lock the adjustment handle all the way down and eliminate the gap between the collar and the pusher block.

One other thing to look at is the bearing on the motor that rides in the pusher block yoke. By loostening the set screw, you can move this part on the motor shaft and affect where it rides in the yoke. From the factory mine wasn't centered on the yoke, and needed a bit of tweaking so that it was centered as it spun.
Highlander
 
Stoker Coal Boiler: Harman VF3000 Sold
Hand Fed Coal Stove: Vermont Castings Resolute
Coal Size/Type: Nut
Stove/Furnace Make: Harman
Stove/Furnace Model: VF3000 Stoker Boiler

Re: Harman stoker expert?

PostBy: coalkirk On: Sat Jul 26, 2008 9:01 pm

OK, I have solved that mystery but now I've got a new one. After a couple of hours of trying different things like putting spacers under the stoker mounting plate to lift it up ( that increased the travel backwards but reduced it forwards) and adding spacers between the pusher rod and the yoke paddle (couldn't get that to work any better), it finally became apparent to me that the distance between the yoke arms was too great. The cam rides in those yoke arms and the contact with the cam bearing on the inside of the yoke arms is the action that moves the pusher back and forth. Some how, the yoke arms had spread apart and that was the slop in the travel. I removed the yoke, placed it on the work bench and "adjusted" it with a hammer, closing the distance between the arms. Now I've got full travel and the buck coal feeds fine. The new mystery is how did the yoke arms get spread apart? Anyway, the boiler is working fine but I'm getting cold feet about buying 24 tons of buck since I couldn't test it under real world load conditions. I'm leaning toward getting rice and a small quantity of buck to try when it gets cold.
Thanks everyone for your help. It's really great to have a bunch of guys available so quickly to bounce things off of. My wife will listen , but she's not much help otherwise on stoker problems. ;)
coalkirk
 
Stoker Coal Boiler: Harman VF3000
Coal Size/Type: antrhcite/rice coal

Re: Harman stoker expert?

PostBy: lewis On: Sat Jul 26, 2008 9:35 pm

I wouldnt use 24 tons as a starting point for an experiment, I'd be darn sure I likedhow the buck fed and burned before I got that much mine does fine with RICE
lewis
 
Stove/Furnace Make: Harman
Stove/Furnace Model: Old Model Magnum

Re: Harman stoker expert?

PostBy: coalkirk On: Sun Jul 27, 2008 7:22 am

Well yesterday was an interesting day. Started off with a left over part. Got that resolved. Then my feed adjustment was unexplicably limited. Got that resolved. I came to my office to post what I found and how I fixed it. When I went back down to check the boiler, I had a hopper fire. :shock: No visible flames but plenty of smoke coming out of the hopper. I only had a pound or so of buck in the hopper luckily so it didn't take too long to empty it and get things under control. So my experimenting with buck is over. Coalberner warned my that might happen if my draft wasn't real strong. The boiler had reached its setpoint and gone into idle mode. In idle mode the combustion fan shuts off. The fire followed the feed path right back to the hopper. This happened in about 10 minutes. So I know during cold weather conditions my draft would be stronger, there are times when the weather gets more moderate and my draft would be less. So I'm glad I tested in summer conditons because it dramatically showed my what happens with buck under poor draft conditions. I know Matt had burned buck in his Harman stoker sucessfully but he was running the combustion fan continuosly and using a coal-trol.
Gee that was fun. ;)
coalkirk
 
Stoker Coal Boiler: Harman VF3000
Coal Size/Type: antrhcite/rice coal

Re: Harman stoker expert?

PostBy: Devil505 On: Sun Jul 27, 2008 8:19 am

coalkirk wrote:When I went back down to check the boiler, I had a hopper fire. :shock:



That doesn't sound like any fun at all Terry! Glad you caught it!
Devil505
 
Stove/Furnace Make: Harman
Stove/Furnace Model: TLC-2000

Re: Harman stoker expert?

PostBy: Adamiscold On: Sun Jul 27, 2008 9:20 am

Maybe try mixing the buck with some rice to see if you can get a better result? Jerry from LL said I could use a 30% mixture of buck with my rice and it should run fine, but it is a LL stove but maybe worth a try?
Adamiscold
 
Stove/Furnace Make: Chubby Sr. Old School

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