Savvy off-road sold? (the unofficial Savvy customer support and Savvy rant thread)

[srimes]

You're not missing anything. The motor develops a torque, and the torque has to be countered by two forces offset from each other. The rope can be one of those forces, but another is required to keep the body from moving.

This. Clamp or weld a bar to the drum, secure the bar, and the winch will try to spin only, without pulling the bar in.

Once the bar hits the winch frame/cross bars, if they're are strong enough to stop the motor, the forces become internal again and the winch will sit peacefully even though the internal forces are very high.

Rope makes a really bad wrench handle. It can't transmit torque, just tension. So we draw our little magic black box around the winch and we only have to analyze the attachment points: rope on the drum and bolts at the feet. The rope only transmits tension so the only reason the winch tries to rotate is because the feet are offset from the rope.

Now if you had 2 lines coming off the winch, one forward and one back, and equally loaded, the winch body would only try to spin much like if there was a bar welded to the drum. The feet would only see vertical forces as the 2 lines would cancel out the horizontal forces.

 

[srimes]

The people want Free Body Diagrams

 

[freedom_in_4low]

lol

The rope tension and the winch deck are not coincident, so the winch becomes a lever and produces a torque moment trying to roll forward. The motion of the winch drum is entirely within the body of the winch. You could wind the rope over the top of the drum and use the "out" button to pull it in, spinning it the other way, and the effect would be the same...only worse because now the rope is up high and even farther from the deck.

If you designed a winch and bumper where the winch was sunk down into the deck and the mounting surface was lined up with where the rope meets the drum, you could all but eliminate this effect. I say "all but" because where the rope leaves the drum is dependent on how many wraps of rope are currently on the drum.

 

[TheBoogieman]

View attachment 562659

 

[JMT]

If you designed a winch and bumper where the winch was sunk down into the deck and the mounting surface was lined up with where the rope meets the drum, you could all but eliminate this effect. I say "all but" because where the rope leaves the drum is dependent on how many wraps of rope are currently on the drum.

So what you would want to do is anchor the top and the bottom of the winch to a plate.

 

[Apparition]

You could wind the rope over the top of the drum and use the "out" button to pull it in, spinning it the other way, and the effect would be the same...only worse because now the rope is up high and even farther from the deck.

Don't do that, @lBasket tried it and it cost him a rope.

 

[lBasket]

Yes read your idiot label stickers on your winch, they're there for a reason.

 

[freedom_in_4low]

So what you would want to do is anchor the top and the bottom of the winch to a plate.

You'd still have a moment trying to rock the winch, you'd just have support on both sides.

To eliminate the rocking moment I think you'd need this:

and if you did this it would reverse the moment so you'd be pulling up on the front of the deck and pushing down on the back.

 

[freedom_in_4low]

Don't do that, @lBasket tried it and it cost him a rope.

That situation comes with a lot of assumptions, one being that the fairlead be properly located according to the new rope arrangement.

 

[Tob]

Y’all missed a great opportunity to put this discussion in Blaine’s Design and Fabrication Chat thread.

Commentary on the physics and design involved has been on point, aside from PNW’s original post (no offense!). However, at the end of the day, any quantitative strength comparison between the new and old design would call for FEA as @sab pointed out.

On that note, I seriously doubt any engineering simulations or calculations are behind the design of aftermarket bumpers and armor (roll cages are a different story, I hope). Engineering judgment, gained from a little bit of background knowledge and lots of experience, and finally trial-and-error real-world testing are more practical methods of product development for this type of company and product.

By paying attention to product design, analyzing the seemingly small details of things, and asking questions if needed, you too can gain some of this engineering judgment and be better equipped to evaluate other designs and new ideas.

 

[srimes]

You'd still have a moment trying to rock the winch, you'd just have support on both sides.

To eliminate the rocking moment I think you'd need this:

View attachment 562676

and if you did this it would reverse the moment so you'd be pulling up on the front of the deck and pushing down on the back.

View attachment 562677

Or send the line down between the feet, and the feet will always be in compression. But we want to pull forward, so turn the whole thing 90 degrees. Maybe something like this:

 

[PNW_LJ]

Another key component of an aluminum bumper to be used in the rocks, is the front corners and their reinforcement.

6061 T6 aluminum, which is the material of choice for our application (we can also talk about why that is), is not the easiest to work with, and a proper bumper will be designed around those limitations.

It's large bend radius (3T = 9/16") means that the front bumper's tight front corners cannot be bent without fracturing.

The obvious solution is to weld those corners. Welding however causes the material to lose it's temper, which significantly weakens it.

The two bumpers that we've seen work around this limitation, incorporate a bolt-on corner guard along the welded area.

The questions I'd like to pose to the group:

Is there a worthy alternative to this approach? Post-welding heat treatment, alternate attachment methods (e.g. rivets), welding with titanium carbide filler?


Further, if a corner guard is the best solution due to cost, time and whatnot, what are the key considerations (material, thickness, weld coverage)?

 

[macleanflood]

Yes read your idiot label stickers on your winch, they're there for a reason.

Like this one?

Don't Warn winches come with grade 5 bolts? That tells you something about the forces their engineers are predicting.

-Mac

 

[lBasket]

Like this one?

View attachment 562714

Don't Warn winches come with grade 5 bolts? That tells you something about the forces their engineers are predicting.

-Mac

I was talking about the pictogram of the right way to spool your line. The sticker they made without words so even an illiterate could understand it. The one I still didn't pay attention to

 

[BlueC]

I was talking about the pictogram of the right way to spool your line. The sticker they made without words so even an illiterate could understand it. The one I still didn't pay attention to

Didn't pay attention to, or couldn't understand it?

 

[lBasket]

Didn't pay attention to, or couldn't understand it?

Hey now... Smart enough to get it right on try #2 when there are 2 ways to put it on at least

 

[srimes]

Another key component of an aluminum bumper to be used in the rocks, is the front corners and their reinforcement.

6061 T6 aluminum, which is the material of choice for our application (we can also talk about why that is), is not the easiest to work with, and a proper bumper will be designed around those limitations.

It's large bend radius (3T = 9/16") means that the front bumper's tight front corners cannot be bent without fracturing.

View attachment 562709

The obvious solution is to weld those corners. Welding however causes the material to lose it's temper, which significantly weakens it.

The two bumpers that we've seen work around this limitation, incorporate a bolt-on corner guard along the welded area.

View attachment 562712

View attachment 562711

The questions I'd like to pose to the group:

Is there a worthy alternative to this approach? Post-welding heat treatment, alternate attachment methods (e.g. rivets), welding with titanium carbide filler?


Further, if a corner guard is the best solution due to cost, time and whatnot, what are the key considerations (material, thickness, weld coverage)?

Dumb question, but are these actually fabricated from T6? Or are they heat treated after? If it's the former then the answer is to do the latter.

 

[jjvw]

Dumb question, but are these actually fabricated from T6? Or are they heat treated after? If it's the former then the answer is to do the latter.

This is my FluxOR bumper.

All my Savvy stuff is also t6.

All the years of discussing how the Savvy stuff is fabricated and why that matters is centered around it being fabricated from t6.

 

[PNW_LJ]

Dumb question, but are these actually fabricated from T6? Or are they heat treated after? If it's the former then the answer is to do the latter.

Like JJ said, they are T6.

My strong suspicion, and what I was hinting at, is that the cost of heat treating a bumper greatly outweighs the savings of starting with 6061 T0, and not having corner guards.

 

[srimes]

This is my FluxOR bumper.
View attachment 562736

All my Savvy stuff is also t6.

All the years of discussing how the Savvy stuff is fabricated and why that matters is centered around it being fabricated from t6.

Thanks, I'm not familiar with that discussion, so maybe this has all been covered before. Typically, the "proper" manufacturing process would be to anneal, shape and weld, and then heat treat.

Of course, you have to work withing your capabilities. The heat treatment process is slow but not that difficult. If @Fluxor wants to advance his capability I'd recommend getting an oven if the volume justifies it, or seeing if there's anyone local who can do it.