For those that haven't seen my rail speeder thread, I have this electronic bell (The silver thing) mounted to the rear of the metal frame/plywood sheathed rear wall. I just acquired a bronze, air controlled bell that I want to replace it with. The bell weighs appx 50lbs, and the ringer that goes inside it probably weighs another 5-10. I would replace the L brackets that are holding the current bell with a welded steel bracket, that would have the same footprint as the two L backets, just one piece.

My question is, would the plywood be able to hold that much weight without failing? Should I get a square steel plate to put on the other side to distribute the weight, rather than just the bolts with washers?

? Plywood thickness ? Yes to plate. If plywood is old, use new multi ply exterior grade to replace.

I knew I forgot something. I believe it's 1/2". I'll double check when I get home. It's old plywood but it's always been painted.

I think it would be OK. How hard would it be to replace with a thicker piece in that section if you are concerned about it?

It wouldn't be horrific, just pain in the ass. I'd have to drill the rivets out, cut, drill and re-rivet (or attempt to). Then repaint.

I'm also debating just doing a couple long strips of steel between the angle stock frame. To allow the angle stock and the wood to hold it in case it starts pulling.

Tying into the angle stock frame also seems like the best idea yet.

How much heavier is the bronze vs the one you currently have, just curious are you adding 10 or 40 lb to the mounting surface.

I would think a metal plate on each side would help distribute the load, will you tie that plate into the metal frame for better support, which would stiffen up the wall as well.

The electronic bell weighs maybe 20lbs

50# is too heavy for that kind of mount to 1/2” plywood, even new plywood.
Making it a double thickness of plywood, at least 6” bigger on all sides would help it support that weight. In the end I have doubts about even this as a long term solution.

How many bolts does it use to attach to the plywood?

If it’s just one probably not, but if there are 4 or so then yes it should hold easily. If your concerned about it use large washers on both sides of the bolts to spread out the load.

That’s too much weight for 1/2 plywood. Can you make a metal plate to go on the inside so the plywood is sandwiched between it and the mount?

quote:

Originally posted by ryan81986:
I'm also debating just doing a couple long strips of steel between the angle stock frame. To allow the angle stock and the wood to hold it in case it starts pulling.

This is a good idea. If it wouldn't cause issues on the inside, angle iron would be better than flat strap for your two strips as it is much more rigid.

 
A plate on the backside would be helpful, and the bigger it is the more so. Steel is not necessary, unless space is an issue. I would use a plate of 3/4" plywood.

Might also depend on the bell geometry as well as its weight - how far away from the back wall that weight will be. If it's way out, that'll put more torque on the mount (trying to pull out the top screws) than if it's up tight to the mount.

If needed, could a metal backing plate be put on the inside?

Are there any corrosive effects that should be considered when mounting metal to metal ?

I'd consider a piece of 2X something, maybe even pressure treated and painted to match.

Especially if it sits out all day and night.

But then you you have extra special nuts, washers and bolts.

Hopefully I'll answer all of the questions here. I'm completely open to all options.

I could use another plate of plywood on the inside instead of steel if that would work. It would get close to the passenger's head but not enough that I think it would cause an issue.

With the size of the bell it will likely stand out appx 1-1 1/2' from the back of the car.

The current bracket for the E-bell uses 4 bolts to hold it to the car, and 4 on the bell itself as well. The way the air bell is designed, as it would be a single bolt that is also part of the ringer assembly.

I have included a photo of the inside so you can see what I'm working with. Excuse the mess, I'm in the middle of doing work to it as well.

My thought for this is, looking at the picture of the inside. Use either flat or angle steel on the inside, bolted to both the bracket on the outside and the angle steel on the outside, or at least cut long enough so it's touching the angle steel on the outside for extra support.

Is there are way to put a small gusset underneath it? Would eliminate any fear of failure.

The inside picture helps. It looks like a single piece of plywood riveted to an angle iron framework.

I don’t see why that 1/2” vertical plywood won’t hold the bell and ringer. Even with a bracket holding the bell out from the plywood, most of the load is being born by the surface of the bolts bearing on the surface of the holes in the plywood. All the nuts and washers are doing is just keeping the bolts from falling out, which I’ll bet you could do with your fingers by themselves. In other words, there isn’t much force pulling the bolts perpendicular to the plywood and adding a backer plate is not needed. Most of the force is parallel to the plywood.

My question is: is the angle iron framework up to the task of holding the bell and plywood up?