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Highway Trucks and Trailers On road trucks and trailers single and twin axle trucks.


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  #21  
Old 07-23-2015, 09:22 PM
ricm ricm is offline
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Default Re: Tri-axle half pipe tipper trailer

I figured time for an update....only 10 months since last one....but 2x house moves later.....



got all the parts made so stripped the trailer right down to get all the Aluminium bits anodized. Now in the process of final build:











Close up of right hand side 'tool box', contains the battery pack for the motorized legs









Some technical challenges...



1) tipper drive control

I originally designed a relay H-bridge for the tipper control (shown earlier in this thread as a small circuit with 2x blue relays side by side), the advantage being that the motor receives maximum power from the battery. This tested fine in manual 'over-ride' mode, and the relays also worked fine with the wireless control when not hooked up to the motor. I found that with everything connected up for final test, the relays would click on and off at high frequency when using the wireless control....but all still OK in manual over-ride mode. After some head scratching, I realized that the motor is drawing too much current at the instant of being turned on because it is, for a short time, effectively a short circuit (the stationary motor has no electrical resistance...only when the motor starts to turn, thereby creating a back EMF, does it have some electrical resistance). The voltage was drops right down below what is needed for the wireless control board to work (the wireless controller and the motor share the same battery pack), therefore the whole thing was shutting down, relay turns off, voltage goes back to 7.2V, then the relay comes back on and the cycle starts again. Testing with separate batteries for motor and wireless controller, which worked fine, proved the point....



So, I've had to revert to finding a basic speed controller with limit switch inputs for both directions (my motor and screw drive is powerful enough to do some damage if it over-runs the mechanical limits of the tipping mechanism!)



http://www.robotpower.com/products/wasp_info.html



The speed controller prevents the initial current surge to the motor, thereby making sure that the wireless controller will always have enough power from the same shared battery.



It also means that I've had to completely rebuild the manual over-ride control, which now consists of a servo tester which can provide a signal to the ESC instead of the wireless controller. You can see this at the bottom of the pic of the underside of the trailer. This will all get built into the left side 'tool box'.



Learning point....for big fat motors, use a dedicated power supply if using a direct 'switched' control (like a relay) to protect anything else from current surges. Otherwise ESC is the way to go.





2) axle heights

this chassis was based on the container trailer, with the whole axle set moved forwards by 1 axle spacing. If you have a container trailer, you may have noticed that the front axle is often just off the ground because I don't think Tamiya quite got the axle heights right. Effectively, the trailer isn't quite horizontal when hooked up to a prime mover and the suspension doesn't allow for the difference to be absorbed. This design problem becomes more obvious with a shorter trailer (like I now have), since the chassis sits at more of an angle. So I added some spacers between the axles and the springs to allow the trailer to sit at the right angle whilst also allowing full movement in the suspension. Without the spacers, the suspension system does take up -some- of the inequality but it is then limited as to how much more movement exists for a bumpy road surface. So no spacers on the rear axle, 3mm spacer on the middle axle and 6mm spacer on the front axle. This is why there is more clearance between the wheel and the arch at the front axle compared to the rear axle. It also meant that the king pin was a the right height for the auto-support legs to work, which are sensitive to too much variation with the height of the coupler on the prime mover....



Next update....hope to have chassis fully built, all wiring installed and tested. Yet to get the bin powder coated (white)
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  #22  
Old 04-15-2016, 03:39 AM
ricm ricm is offline
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Default Re: Tri-axle half pipe tipper trailer

should have uploaded these a while ago....build ended up being a bit more $$ than I budgeted for but really happy with the result :-) I did a dump test with over 10kg load at the very front end of the tipper body. Worked so easily I wondered if I had well over-engineered the whole thing. But rather that way than the alternative!









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  #23  
Old 04-15-2016, 04:20 AM
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bigford bigford is offline
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Default Re: Tri-axle half pipe tipper trailer

looks great ric, glad to see you posting the build
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  #24  
Old 04-15-2016, 05:48 AM
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Snowman Snowman is offline
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Default Re: Tri-axle half pipe tipper trailer

Great workmanship
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  #25  
Old 04-15-2016, 09:50 AM
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RCP57 RCP57 is offline
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Default Re: Tri-axle half pipe tipper trailer

Your ears must have been burning!lol I was just looking at a small piece of your tub that I had saved yesterday. Great to see the finished product after all of this time. What did you end up using to coat it?
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  #26  
Old 04-15-2016, 06:30 PM
ricm ricm is offline
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Default Re: Tri-axle half pipe tipper trailer

My local powder coating place had a minimum charge which was more than the cash price from the car panel shop. So ended up with 2-pack automotive paint job.

I'm taking it out for it's first public showing tomorrow at an earthmoving expo where our club has a stand. At least the RC excavator owners will have something to load up!
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  #27  
Old 04-15-2016, 10:06 PM
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Default Re: Tri-axle half pipe tipper trailer

whats the story with the cylinder??
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  #28  
Old 04-16-2016, 12:17 AM
ricm ricm is offline
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Default Re: Tri-axle half pipe tipper trailer

5-stage hoist is cosmetic only - no hydraulic oil anywhere. Having built the trailer before I got it painted, it just looked wrong without a hoist. I've seen plenty of rigid trucks with the lifting mechanism under the bin, but never any semi-trailers. So it's just to add some realism even though it's not functional
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  #29  
Old 12-17-2017, 08:31 PM
Redmun205 Redmun205 is offline
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Default Re: Tri-axle half pipe tipper trailer

Mate that looks awesome. great build.
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  #30  
Old 12-17-2017, 11:06 PM
bigpipespete bigpipespete is offline
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Default Re: Tri-axle half pipe tipper trailer

What a nice looking rig , how much does the trailer weigh ?
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  #31  
Old 12-18-2017, 03:37 AM
skeeter skeeter is offline
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Default Re: Tri-axle half pipe tipper trailer

Did you buy, or make the screw drive for the tipper?
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  #32  
Old 12-18-2017, 11:16 AM
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Giuseppe Giuseppe is offline
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Smile Re: Tri-axle half pipe tipper trailer

Fantastic job,i also built a half pipe,for my Man tamiya 8x8 self made,with 2 front tract axles;But your work, is extremely precise.Regards : D:mascella:
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