Sherman Cooling Mod

[Mantraguy]

Yes, I have created a solution to a problem that doesn't exist. ;-)

It's well known that the Sherman runs fairly cool, and it's not easy to overheat the control board (I have the V3 Sherman). So, my primary reason for creating this design wasn't actually centered around cooling the Sherman, but that I wanted to gain more experience with 3d modeling software.

Having said that, I've always looked at the location of the cooling duct on the front of the Sherman and thought that it couldn't be very effective, as the flow of air into the vent was blocked by the headlamp. I thought it might be an interesting experiment to see if I could increase airflow (and therefore, cooling) by creating an air scoop that funneled air into this duct from above the headlamp, or possibly from the sides. So, that was the goal of the design.

It took a few iterations to get the right shape and dimensions for both the input and output to line up with what existed on the Sherman. I also noted that the stock air duct does not funnel air directly over the control board. The control board itself is secured to a large, aluminum heat sink that has cooling fins on the bottom, and that's where the air duct channels the air towards - the bottom of the heat sink. I also don't know exactly where the temperature probe is that gives the reading to EUC World, but it seems to make sense that it's somewhere on the top of the control board.

I did a few rides before installing my cooling duct, and recorded the displayed temperature before, during, and for a few minutes after a particularly hard ride. I did a variety of rides including hill climbs, faster speeds uphill and downhill, and a few other types of terrain that would make the wheel work hard and therefore generate more heat on the control board. I then installed the new cooling duct and did the same tests (on the same day so ambient conditions were identical). What I found was that, although the temperatures of the control board weren't really any lower during the period of hard riding, the duct seemed to allow the control board to cool faster than it did without (perhaps on a longer duration of hard riding the temperature would stay cooler; I didn't try this as I couldn't find a long enough steep hill around here). On some rides (up a long, gradual hill on paved roads, for example), the temperatures didn't really increase that much so the difference was less noticeable. On hard climbs at slow speeds, more heat seems to be generated and the cooling mod becomes more effective.

For example, riding up a steep, fairly slow dirt trail increased the control board temperature from 43'C up to 51'C both with and without the cooling duct. However, taking temperatures at one minute and two minutes after, while descending at 35km/h on a smooth road, the temperature in stock format was recorded at 50'C after 1 minute and 49'C after two minutes. If I repeated the test again with the cooling duct installed, the board temperature again increased from 43'C to 51'C during the climb, but on the descent it cooled to 47'C after one minute and 44'C after two minutes. Therefore, it seems logical that the cooling duct helps to keep the big aluminum heat sink cool, which then is able to suck heat away from the control board faster.

For now, I'm going to keep the duct in place and see how it fares on Marty's California tour next month. I may be able to compare temperatures with other Sherman owners on the same ride. I just thought it was an interesting experiment, and it does seem to work although these temperatures probably don't do any harm to the control board anyway, so it's not really a problem that needed addressing in the first place.

One final note is to the print quality of the duct - it's printed from PETG and it's a bit of a challenge since there's really no flat surface to stick to the build plate. Therefore, some supports were required inside so the inside edges are a big ugly. I'll play with some settings and see if I can get a nicer looking print some time.

 

[Whitebeard]

200 lb rider here. I know exactly what you mean, and I did a few days of Marty’s tour last year. I really like your idea. I’ll see you in the tour next month!

 

 Just to add a little more details here. There was the Mt. Wilson highway 39 ride where I was consistently overheating. So I had to let it cool off at least 10 times here. So I really hope you succeed in solving the cooling issue for heavier riders like myself.

Edited September 20, 2022 by Whitebeard

[Mantraguy]

1 hour ago, Whitebeard said:

200 lb rider here. I know exactly what you mean, and I did a few days of Marty’s tour last year. I really like your idea. I’ll see you in the tour next month!

 

 Just to add a little more details here. There was the Mt. Wilson highway 39 ride where I was consistently overheating. So I had to let it cool off at least 10 times here. So I really hope you succeed in solving the cooling issue for heavier riders like myself.

I admit I didn't look very hard but I didn't think the Sherman was a wheel that suffered from overheating issues! I'm also a lightweight (150lbs all geared up) and live in a place that rarely sees temperatures in the high 80°F range, and low 90s is the very hottest we ever get. So, I doubt I'll ever have overheating issues on my own Sherman.

If you'd like, I'd be happy to print you one for your Sherman and you can see if it makes much difference. It's only held on with double-sided tape, although you do have to loosen your front light a bit and pivot it down to get the duct in place (you can pivot it back up once it's in) - so it's something we could easily fit in a parking lot before one of the rides. Send me a PM if you'd like to try it and I'll send you a list of colours I can print. If it doesn't help, I won't charge you; if it works, you can pay me whatever you think is fair.