As requested. I was actually able to dig up some old pics detailing the build posted on the mog message exchange in 2006. The story began in 8/2005 when Ben Palmer in Helena alerted me to a blower head and engine pack rusting away behind a building at a car dealership in Sun Valley, ID. It reportedly had never been used stateside, just stripped from a 404s and orphaned. Was I interested? Sure, even though its condition was unknown and there would be challenges mounting this on my Case mog. I figured the engine was probably toast at the very least, but for $500 (Ben's cost of hauling) the price was right. Here's a pic of where it sat in Sun Valley:
When I got the blower, I saw that it would not be a plug and play fit to my unimog to say the least. The OEM intended for the blower to be mounted to a 404s not a 406, the big difference being that the 404s rear deck is ~2' longer than the Case deck, and quite a bit lower to the ground. Before I got too far into tackling these issues, I figured I'd see if the old OM321 (6 cyl turbo) would even turn over. The crank turned freely. I changed out the oil and drained and bled the fuel system and then came the moment of truth...would it start? I rigged up a starter button and cranked away. It wouldn't start. It would almost catch, cough a bit, but wouldn't get going. Then suddenly there was a loud *KAPOW* followed by the smooth hum of the turbo winding up and an even idle. The explosion was a rat's nest being ejected from the exhaust pipe. It actually partially tore the flapper off the stack.
Okay...now that I had a working engine pack, I had to figure out how to mount it on the Case deck and how to transmit power to the blower head. I ended up chopping off the front ~2' of the engine enclosure where the rusted fuel tank lived. Then, I split and lengthened the chain case 18" so it would clear the undercarriage:
Since the blower didn't have its original driveshafts or bearings, I had to devise an alternative driveline. I opted for off-the-shelf ag PTO shafts, one on the rear and one on the front, mated across a bearing carrier mounted to the skid plate that protects the auxiliary hydraulic pump at the base of the transmission:
Next, I had to fabricate a lift system for the blower head to mount to the Schmidt plate. Nothing fancy here, just some steel and hydraulics. I purchased 2 loader cylinders for the lift, and used some old single-acting snowplow cylinders that I had laying around for the chute angle adjustment:
Lastly, I had to devise a way to remotely control and monitor the engine, and operate the clutch. The original design had various rods and levers passing into the 404 cab to tackle these tasks plus shifting the 3 speed transmission. I've not found a need to do the latter.
So this is the blower's 10th winter of service for me and still going strong. The only modification I've made is to add an additional 1400# counterweight to the Case deck hooks on the back.
So the power pack has a 3 speed transmission linking it to the chain drive? I suppose I could see a need to adjust impeller speeds, trading cutting force for cutting & eject speed in light fluffy stuff but that sounds like an added step which in typical unimog fashion would require the co-driver and 3 6" 3-ring binders of calculations and support tables.
Looks like you did a great job of adapting and overcoming.
Thanks AC. Yeah, 3 speed transmission outputs to the chain drive. I can't remember the gear ratios off the top of my head. Ha! I agree with your assessment of German optimization. There are, of course, several degrees of freedom to consider in maximizing tonnage (gear ratio, engine speed, forward speed, snow type, snow depth...n...n+1...). For me, 2nd gear fits the bill for most of my use. Things get a little too vibratory in 3rd gear, probably due to exceeding the PTO shafts recommended rpm, and 1st gear is really, really slow. One might assume that 1st gear naturally delivers the most torque and is therefore best for wet heavy snow, but that's not the case in my experience. In those conditions, you want to keep the blower loaded up and moving a lot of snow through the chutes, otherwise they will clog and oblong blocks of compacted snow will just fall from the chutes, kind of like a giant PEZ dispenser. In any case, conditions don't change that much over the length of my driveway where I need to shift on the fly. Very cool system of rods, turnbuckles, and levers they employed to do the shifting though in the original setup.
Great job! The reason you had to add so much length on the chain drive is that on the 404 they had room for the first PTO shaft to go above the rear axle. It goes down at a fairly steep angle to the first of two carrier brackets. From your photos it is clear there was no room on a 406 for that.
The motorized throttle is great, much better than the original cable with its pulleys, etc.
Are you able to start it with only glow plugs in severe cold, or do you use a swingfire? (I pretty much have to do some preheating unless stored indoors.)
Your unit must also be from the early 1960's, there is a note in my Beilhack manual that seems to indicate they switched to the OM352A in February 1965.
Thanks Y404. Oh wow, so the PTO shaft goes above the rear axle. I think I remember seeing a photo of it at one point. I'd be interested seeing photos of your driveline and any showing the shifting mechanism, etc.
Yes, the nameplate on the blower head indicates 1964 as the date of manufacture. And I almost always had both the mog and blower engines plugged into 1500W coolant heaters. Below about 10º F, my mog has little chance of starting without ether. However, the glow plugs always resulted in a quick start whatever the temperature. Your OM352A has significantly more horsepower than the OM321 I believe. I think the nameplate states 111 ps which is only about 110 hp.
I just saw your other post with your new shop, so let me rephrase my question: In the OLD days, how did you start the blower engine on cold days? Nice shop!
I may have posted this a couple years ago. On the prior page of the op manual it says,
"For a driver without clearing experience, the shown diagram (picture 22) is of special importance. It shows the clearing speed in relationship to snow weight and snow height for a single length of a throw."
Thanks for these figures Y404! Very interesting. So the blower head is mainly supported by struts that attach to the front axle? That actually makes sense to me given that it's pretty heavy, especially for a 404. I kind of wish mine were mounted that way, well except of course for the quick-attach benefit of mounting it to the Schmidt plate. I notice with the blower head and the plow, a lot of lift clearance is lost in the suspension...implement go up, mog go down...and I have the heavy double springs.
I've seen the performance graph but never studied it until now. I'm not sure that there is a lot of high science that went into it, or maybe snow enjoys a very simple relationship ( ƒ(forward speed) = N/depth) with snowblowers which makes sense. In a nutshell, the graph states that, for a given snow density, you have to drive slower in deep snow, and that the slower you go the farther you blow it. Also, the denser the snow, the slower you must go and you will not throw it as far.
What snow conditions do you usually have? I'm guessing fluffy powder given your location. Our blower loves that stuff, eh? It's a good design given it's intended purpose of clearing fresh snow from airfields. I think that there are better designs for a range of conditions. I am a fan of the 2-stage (auger and fan), and see that Schmidt has moved to that design for their dedicated machines. I scratch-built the blower in the video many years ago, and love the performance in the full range of snow conditions that we get around here. I've thought about upscaling the design and making one for the unimog.
Generally we have either powder, or wind-blown drifts that eventually set-up hard. I do OK if I get into those drifts soon after they form, say 8 to 10 hours. If I wait too long, the snow becomes so hard you can "almost" drive on it. Then the props cut into the drift until the front lower edge of the blower gets into the hard stuff, at which point either the blower starts to ride up (the lift cylinders are single-acting), or the mog just can't move forward. I can break the drift up a little with a V- plow (mounted to loader arms) and then blow it. If we're in a weather pattern with a lot of wind, the last thing I want is big plow berms. BTW, like that ASV blower, but at that width, it would take me a long time...
My blower is off right now, but I have a couple photos that are pretty close to what I'd show you:
Hidden behind the lift cylinder is a rod (barely visible) that fits into the upward facing hole on the front bumper frame. There is one on both sides. These rods are what hold the blower head up when travelling or when the power pack isn't running.
Man, no kidding! The non-rotating chute is a big drawback. Fabricating some sort of rotating chute is on my list of things to complete someday. Looking through my stuff, I see I went as far as to take measurements and start a design to fit our blower head. It's an odd geometry to start from though. Thanks for the pic Trev.
I like your approach better than a pair of tilting forward chutes. Locking the chutes in the vertical position frees up a hydraulic circuit for the rotation. I'd maybe add a hydraulic top flap to limit the throw when needed. I have a bunch of obstacles (solar panels, greenhouse, etc.) that are on the leeward side. When passing those I often have to blow into wind, which is a visibility-killer even with just a breeze.
I am right there with you on the visibility! It's the one key variable not plotted on the performance graph...lol. In powder snow, poor visibility is my most limiting factor with regard to forward speed. I could go a lot faster if I could only see where I was going. At least you have the circular wipers. The stock 406 wipers are woefully inadequate to clear the blower-generated blizzard off the windscreen. A top flap would definitely keep a lot of ejecta down and out of the wind.
This idea flashed by while reading of the drop box mods: On the 406's original PTO box, if the box were modified to remove the gear that couples to the cluster gear in the trans, seems the original front and rear PTO shafts could be coupled together (forward lever position: "both") allowing the power pack to be coupled through the truck, rear to front. Since the PTO was rated at 75 hp, that would handle many snow cutters.
Of course the PTO would be disabled for all other normal operations.
That's an interesting idea. I know there have been some discussions about possibly powering the transmission via a hydraulic motor over the PTO, but not reducing the PTO box to a carrier bearing.
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