Fan Reversal

Dr. Walt · May 13, 2017

Didn't want to hijack Crackerjack's Post.

I can understand the reasoning for drawing air IN through the radiator on an automobile, because at Speed you get to take advantage of the RAM effect of the air forcing it's way through the radiator. - But with Tractors traveling slower where you don't get the RAM effect, and the fact that most older tractors don't have their engines compartmentalized like an automobile, wouldn't it be more advantageous to REVERSE the fan blades so that they push the air FORWARD through the radiator, thereby lessening or negating the chance of plugging the radiator with grass, chaff, and other debris normally encountered while operating a tractor???

:>)

coshoo · May 13, 2017

Story is told in our neighborhood of an old cat-skinner who bought a brand new D8 Cat back in the '50's (he didn't much care for that new-fangled hydraulic blade, so made them put a cable blade on it, like he was used to). But it would overheat- not suddenly, but over the course of a half hour or so of running. And not just sometimes- but every time he used it. Local dealer couldn't figure out why- until a mechanic was standing in front of the rig while it was running, and became aware that hot air was hitting him. Turns out that the fan had been installed backwards at the factory, and it was blowing out air from around the engine. And as the engine warmed up, the air from around the engine got hotter, which make the water in the radiator get hotter, which in turn made the engine hotter- the proverbial "vicious circle". Turned the fan around, problem solved.

Graham of New Zealand · May 13, 2017

There are plenty of bulldozers etc using pusher fans. We have one, a mitsibishi BD2F. No problems. Maybe needs higher capacity fan to overcome engine heat

bradley martin · May 13, 2017

Some of the newer self propelled forage harvesters and combines can reverse the airflow while running to blow the chaff and dust out of the radiator. As coshoo's post shows, drawing warm air from around the engine presents its own problems.

Bob Bancroft · May 13, 2017

Interesting subject.

The way I use my heavy truck, mostly early in the morning, on level roads, the fan rarely runs at all.

My dozer fan pushes out the front. Even though the engine is covered, screened, and shrouded, it's surprising how much junk gets drawn in through to the radiator. I think it was probably a lot simpler and cheaper to screen the front of the radiator, than the rear. Plus, more obvious to see the need for cleaning, and easier to get at to clean.

deeretails · May 13, 2017

Many years ago I worked for a utility company that used Wayne Roy backhoes with gas engines. Because of the area these were driven to job sites, not trailered. One of these brand new units worked just fine digging but every time it would travel from site to site it would overheat. Turned out it had a pusher fan on it, and at road speed (12 MPH) the air would stagnate in the radiator. Took us a while to figure it out, replaced the fan with a puller fan all worked well after that.

Reversing a fan does not change the direction of air flow. Pusher and puller fans are built opposite of each other.

sms · May 13, 2017

Many dozers have fans that can be changed for the seasons.

Aaron SEIA · May 13, 2017

The 88 series IH tractors had that air flow. I believe they put the fan in front and had the drive shaft go through the radiator.
AaronSEIA

Roger Tomfohrde · May 13, 2017

I don't think that they mounted the fan in front of the radiator. The brothers 3688 it draws the air down from the top of the hood and out the front but if i remember correctly the fan blade is where it
always was on the motor. Our New Idea Uni system 701-704 had a reversed fan blade and blew the heat out the back, but with the combine would suck the schaff up against the screens if the wind was the wrong direction.

Bruce from Can. · May 13, 2017

Neighbour had a Uni to forage harvest with. They put chopped hat into a Harvestor silo , so the hay was always quite dry when chopped . He told me that he would frequently had the harvester on fire. Fine dust would blow on to the exhaust manifold , so he always kept water on board to douse the flames .

Two Dogs · May 13, 2017

Just turning the fan around does not reverse the air flow, unless you also reverse the rotation.

Brendon-KS · May 13, 2017

To reverse the air flow direction by turning a fan around is sort of like saying that you can take a right-hand thread nut and turn it over to make it into a left-hand nut. It just doesn't work that way. Think of a fan as a big, flat screw and it becomes clear that the story defies physics. The only way to reverse the air flow from a fixed-blade fan is to rotate it the opposite direction.

old-9 · May 13, 2017

Ford tractors had an option of a reversed fan. My 1941 has a reverse fan, it cools just fine and is cooler in the summer and in winter, that cold blast of air does not blow on you. This is a 6 blade fan made as a pusher or puller. joe

Geo-TH,In · May 13, 2017

When it's very hot outside, I heard the gas boiling in my Jubilee because the heat from radiator hit the gas tank. The exhaust manifold is under the tank too. The heat is trapped under the hood.

When I replaced the gas tank, I used aluminum and made it cover the exhaust manifold and keep the heat from manifold away from tank. If the aluminum didn't work, I was seriously thinking of getting a pusher fan.
geo

John B. · May 13, 2017

With the engine compartments closed up as they are now on new tractors you would be pushing all that engine heat thru the radiator and not get any cooling affect. Then too if you get an oil leak or fuel leak the fan would coat the radiator causing it to clog even worse and not as easy to clean. No matter where the fan draws the air from you're gonna have clogged screens to clean sooner than later. Back in school 40 years ago it was brought up that "why don't they put the AC condenser behind the engine radiator so the engine would cool better?" Teachers reply was "Well your AC wouldn't cool much at all then!"

Roger in Iowa · May 13, 2017

Yep, the 88's blow out the front. Neighbor has had to overhaul his twice because radiator plugged when using a grain
vaccuum, engine overheated and could not see the plug. Tractor is operated with no one in the cab to watch gauges or
warnings!

Traditional Farmer · May 13, 2017

Seems to me if the engine compartment were closed up then pulling the hot air out of the engine compartment and pushing it out the front would be as good or better than
pulling the hot air off the radiator and blowing it into the engine compartment.

moresmoke · May 13, 2017

The older Cats had reversible fans. There was an access panel you took off the fan screen, then pushed in on the end of the blade and you could twist the blade around to change direction.

Brendon-KS · May 13, 2017

The efficiency of a cooler has a lot to do with the difference in temperature between what you're cooling and what you're cooling it with. If you sucked air off the engine and blew it through the radiator the temperature difference between the air and water would only be around 30 degrees which would mean a very inefficient cooling system. On the other hand, when drawing in ambient air this difference is more like 70 or 80 degrees. Also, the surrounding air temperature doesn't effect the engine's heat rejection by very much so whether the engine is surrounded by 100 degree air (ambient) or 150 degree air out of the cooler doesn't make too much difference in the required cooler size.

DR. EVIL · May 13, 2017

Fan on the 3x88 and 5x88 was ahead of the radiator, pulling air thru a radiator creates a smoother airflow that pulls more heat out of the radiator. Turbulent airflow pulls less heat.

Far as an 88-series tractor over heating on a grain vac, it would overheat with a conventional air flow 2-3 times as much, less dust/dirt above the hood compared to out in front of the tractor.

I remember doing fall fieldwork with the 4010, about every 2-3 rounds have to stop and clean side panels of trash and corn shucks. Could tell by the temp Guage.

I forget the year, think it was late 1970s, Farmshow magazine said on one WEEKEND during fall fieldwork season 3-4 big new Deere 4wd's caught on fire from trash being carried up by tires and blowed back against exhaust manifold by the radiator fan where it caught fire and burned the whole tractor.

Determined · May 13, 2017

A customer I used to do service work for had a diesel generator that was equipped with a pusher fan.
As the engine was enclosed top and sides in a cabinet the fan did a good job of creating a low pressure zone inside the enclosure.
Depending on the way the wind blew it at times would be sucking in the oily/sooty exhaust, as this passed through the radiator it would build up along with whatever dust that was present and plug the rad so bad that the only feasible way of cleaning it was to remove it and have a rad shop tank it twice a year.

GVSII · May 13, 2017

(quoted from post at 05:02:21 05/13/17) When it's very hot outside, I heard the gas boiling in my Jubilee because the heat from radiator hit the gas tank. The exhaust manifold is under the tank too. The heat is trapped under the hood.

When I replaced the gas tank, I used aluminum and made it cover the exhaust manifold and keep the heat from manifold away from tank. If the aluminum didn't work, I was seriously thinking of getting a pusher fan.
geo

Odd that you had to make a heat shield for your Jub.I'm pretty sure it was delivered with one.Later 100/01's had a shield from new.

pete 23 · May 13, 2017

Two big problems with the front air flow system used on IH 50 series etc, was really tough to clean them good. The washing method recommended by IH just makes a big mess. Need to pull side covers, lift oil cooler and air cond condenser out of the way to do a decent job. The other problem was that the incoming air always takes the shortest, easiest route and most of the air goes through the upper part of radiator and not the lower where the air cond condenser is located. I always find higher operating pressures on those air cond than on other models.

Of course, the Magnums were no fun to clean either due to poor access to front of radiator.

ohiojim · May 14, 2017

the small JD dozers had pusher fans, worked great, had to buy reversible fan to get a puller for winter

Fan Reversal

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