My Senior design project - a "Swamp Thing" tracked vehicle clone

[texasranger556]

I would probably go with an electric clutch, brand new for $100 or less depending what brand/style you go with.

 

[K5lwq]

Not really Arly. I've been playing around a bit on the design of Snowzerblower which I may or may not build:

View attachment 710657

Here's a design question for the group: when you look at the 5v belt being driven by the 20hp Onan engine, you'll see a belt tensioner device. This will act as a clutch to engage/disengage the blower by tightening/loosening the belt tension. I would plan to activate it with a small pneumatic cyclinder (under the housing) using a three-way solenoid valve inside the cab piped to an air supply. Do you think it work better as shown to push on the belt or should I move it to the inside of the belt to pull on it to tighten the belt? Stay well.

Just like you have it is best. Very effective. Looks like a nice design.

 

[Garauld]

I looked into electric clutches some time ago. I found that electric clutches with 1-7/16" IDs are uncommon and the pulleys tend to be too large for my needs. I have to slow the engine speed down a bit to run the impeller at a reasonable rpm (around 1000) so I mounted the smallest pulley I could fit on the engine shaft.

 

[ArlyA]

When I was putting together a snow tiller design powered via 35HP engine and needed to add a electric clutch to the setup, I looked and looked and gave up searching for a readily available one that could handle that much HP. I eventually found a company in the twin cities MN who built them.

 

[LittleBill21]

no i did not read this entire thing, i will throw this out about the master cylinder booster. my 2000 chevy 3500 express van. uses a master cylinder that is run off the PS pump for boost. it makes a huge difference, on a motorhome chassis,

also prolly dumb question, is all your cad stuff drawn literally from scratch?

 

[Garauld]

From the internet: "Heavy vehicles and cars with very quick-ratio steering boxes typically require higher pressures than lighter and lower-performing vehicles. At idle with the steering wheel static, a typical power steering pump holds about 80 to 125 psi in the output line. Yank the steering wheel a couple of times in rapid succession -- causing the pressure-release valve to flutter open and shut -- and a typical modern pump might momentarily put between 1,000 and 1,500 psi through the lines. Older and lower-performing pumps might run 850 psi of momentary pressure or less, while heavy-duty off-road pumps may sustain 1,600 or more. High-performance pumps can jump to 2,500 psi before the valve releases."

After I installed the vacuum boosters, I hooked up a 2300 psi pressure gauge to the output of my master cylinders and was able to peg it. I feel that should be enough pressure for the calipers to clamp the steering rotors. I do not plan to make any more changes until I play with it in the snow this winter.

is all your cad stuff drawn literally from scratch?

Pretty much everything except for nuts, bolts and other common items - I normally get those models from McMaster-Carr.

 

[KubotainNH]

Do you think it work better as shown to push on the belt or should I move it to the inside of the belt to pull on it to tighten the belt?

Pushing usually works better as the belt ends up with more surface area on the pulley. Looks like a cool setup.

 

[airbiscuit]

What is your air supply for the pneumatic cylinder to actuate the belt tightener?

 

[texasranger556]

I looked into electric clutches some time ago. I found that electric clutches with 1-7/16" IDs are uncommon and the pulleys tend to be too large for my needs. I have to slow the engine speed down a bit to run the impeller at a reasonable rpm (around 1000) so I mounted the smallest pulley I could fit on the engine shaft.

That is a strange size shaft. I've not seen it done before, but I'm wondering if there is any technical reason you couldn't mount an electric clutch on the jack shaft instead of the engine? That way you can size the jack shaft diameter to whatever clutch you come up with...in this case you'd want the biggest pulley available.

Drawback is the torque would be increased by the pulley ratio between the engine and clutch, so you'd have to take that into consideration selecting the clutch.

 

[Garauld]

What is your air supply for the pneumatic cylinder to actuate the belt tightener?

I would use a mini 12v air compressor that I would pipe up to a small tank and a pressure switch - the kind they sell for air horns.