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Ari Holopainen / project5590 | |
| PROJECT 5590 I & II
Table of Contents: A. Project I - A.1. 12-speed 6x4 dump truck - A.2. This is how it is and could be done - A.3. Part II - Cassette dump truck - A.4. Interesting details - A.5. How to play with this toy B. Project II - B.1. 12-speed 4x2 tractor truck - B.2. This is how it is and could be done II - B.3. Semi trailer dump truck - B.4. About semi trailer dump truck A. Project I A.1. 12-speed 6x4 dump truck: Truck has no suspension nor differentials but it has a 12-speed transmission.
This 6x4 truck is based on Model Team 5590 but some extra bricks and technic parts are included to complete this very difficult building challenge. There is also one cheating part: 24 teeth gear is modified to slide on the axle. Cheating part is not necessary while I found a way how to build chassis with standard lego parts by modifying range-change unit. Check next chapter for more info.
A.2. This is how it is and could be done:
How it’s done with cheating part... Like in real trucks this transmission has three separate gearboxes in one driveline: 3-speed main gearbox (which would also contain a reverse gear in real life), 2-speed range-change unit and 2-speed splitter unit. But Lego trucks don’t need any reverse gears, so available gears are: 1L-1H-2L-2H-3L-3H-4L-4H-5L-5H-6L-6H. Cheating part (sliding 24 teeth gear) is shown as light green. You have to note that this is not a drive-ready frame, for example you need to connect rear axle support to auxiliary gearboxes’ frame underneath. You will need two layers of plates including 2x2 corner plates and have to check carefully that plates don’t block splitter’s gear wheels.
You may have difficulties to figure out the construction from these pictures so I recommend to download LDraw file. Note that steering axle is supported by two technic brick 1x1 with hole parts so steering gear is not in the middle of the steering rack. This means that you have to limit steering angle to left a little bit. Despite this limiting steering angle is still greater than original 5590 truck has. How it could be done with standard legos... Later I found out how you can build this chassis without that cheating part (sliding 24 teeth gear). It needed redesigned range-change unit and relocated gearbox frame enforcement parts. So, if you want to build this 12-speed 6x4 lego chassis here is alternative setup for you. I offer only technic and let you design lego truck of your own, but if you build your own truck I want to see pictures of your design. :-) Note that this construction is for high speed lego motor but you can alter motor’s XS(8)-S(16) and outside the frame located XS(8)-M(24) gear pairs.
A.3. Part II - Cassette dump truck:
I’m not sure is this term cassette dump truck right or not. Maybe transfer dump truck rings a bell... But anyway, idea of this truck is that you first leave trailer in the street and go to dump truck itself. Then you drive back to your trailer and take trailer’s box into truck’s empty one. Now you go to dump trailer’s box with your truck while trailer stays in the street. Notable thing is that you don’t have to reverse with trailer at all, so you can easily reach difficult dumping areas. Bad thing is that you need to disconnect and connect trailer every time you want to dump. This 3-axle truck and 4-axle trailer construction causes one interesting problem: how to dump trailer’s box without breaking the law about the allowed axle weights? Trailer’s net load is about a double compared to truck’s net load. So when you take the trailer’s box into the truck truck’s axle weights are far over the limits. Trucks can usually handle this kind of overloads but how about the roads? Nowadays this 7-axle transfer dump truck is out of date. They have increased maximum total weights for the truck and trailer in Finland but you need 9 axles to get maximum load. A.4. Interesting details: You may notice that this truck looks a little bit like Renault Magnum. Reason for this choice is the fact that cabin’s doors are right above the front wheels and can’t be moved forwards because of windshield. This means that cabin steps can’t be in front of wheels where they usually are. So steps are located behind front wheels and the only European truck that uses this arrangement is Renault Magnum. In real world Renault Magnum is a long haul truck and it’s not designed for transfer dump truck use where you need to get out from cabin more often. So Renault Magnum look-alike lego truck is not very good choice but to arrange cabin steps was very problematic. And while lego truck looks like Renault Magnum then its transmission is inspired by 12-speed version of ZF Ecosplit. But if you need sequential transmission for lego American truck this transmission can be also thought as lego version of Eaton Endurant, 12-speed automated transmission.
Other interesting feature is colors of German flag in cargo body and under cabin window. German is old language of technic and German name often says exactly what certain device is. For example Ausgleichgetriebe says it all: aus means out and gleich same or equal. Getriebe is transmission and it comes from verb treiben which has also meaning flowing. And power flow goes through transmission. So in conclusion, what is transmission that has equal outputs? Yes, it’s differential. :-) When you look truck behind you can see Snoopy on his doghouse. That cardboard is actually taken from packet of Snoopy socks. Its background color is almost same as lego’s yellow so it fits good on the backside of the truck’s box. While it’s placed horizontally it gives very kinetic expression. There are also name plates attached to cabin doors. These texts are taken from stickers that pharmacy puts on your prescription drugs. A.5. How to play with this toy: I’m only lego builder so I don’t usually play with my lego toys, I only test them after modifications. But here is some hints how you can play with this lego truck and trailer. Although truck has 12 gears you don’t need them all in normal use. On easy terrain you can drive at maximum speed by using top gear 6H. While transmission has geometrical gear steps high range covers major part of the speed range. So for slower speeds you can shift to 5H or 4H by using only main gearbox. If you need even slower speed and you are going use top gear again after it you can do range shift from 6H to 3H. And if truck has some difficulties to go on with top gear 6H you can make splitter shift to 6L. For normal lego use these five gears are enough. Of course if you are already in gear 6L and need slower speed it’s easier to shift to 5L or 4L instead of 5H or 4H. Warning: while overall gear ratio is 20,00 first gear gives 20 times the torque compared to top gear so be careful in low gears that you don’t break lego gear wheels. This truck has drawbar trailer (also known as full trailer) with two pivot points so it’s very difficult to reverse it. If you steer left while reversing also trailer starts to turn left. So if you want to reverse straight and trailer starts to turn left you steer temporarily to right. This is quite simple. But turning while reversing is more complicated: To turn left you first steer left and trailer starts to turn left. But if you go on like this trailer will turn tighter and tighter. So next you steer temporarily right to get truck on outer radius curve to get drawbar in right angle. Then you steer again left and get trailer to go on constant radius curve. This is the theory but in practise you have to do steering corrections all the time. To reverse straight again you steer temporarily right to get drawbar aligned with trailer. Then you steer temporarily left to get truck aligned with trailer. Too complicated? Remember that real truckers are in cabin and use two mirrors while doing this so everything is mirrored. Yes, it’s difficult and everybody needs practice. When you can reverse 90 degree turn with your lego truck and trailer you are pro lego trucker. :-) Here are two real reversing practice clips with truck and trailer: https://youtu.be/OXKW49Fxq04 and https://youtu.be/MtwEjxbHXY0. Note that mirrors give very limited view so there is a moment in both clips when driver gets out and goes to check where trailer’s right rear corner is. B. Project II B.1. 12-speed 4x2 tractor truck:
This project II began when I wanted smaller splitter step to my dump truck. Original splitter in 6x4 truck had ratios 1,50 and 2,00 giving step 1,33. Gear step 1,25 would give smaller step between two top gears and make some progression in gear steps. My first modified design had ratios 1,60 and 2,00 but then there was no space for 24 teeth gears needed by tandem drive. While truck has no suspension 6x2 truck was not possible so that is when 4x2 tractor truck idea came in. But when I got it ready new splitter couldn’t unfortunately handle enough torque so I had to abandon it and use original splitter. I had already built semi trailer for this truck so I didn’t abandon this 4x2 design. Much later I found out how to get splitter with step 1,25 using ratios 2,00 and 2,50. This splitter turned out be strong enough. So here is 12-speed version II, 4x2 tractor truck.
So, removed axle shortened truck’s length and cargo body was replaced with 5th wheel. Notable thing is that usually 4x2 tractor trucks have low or normal frame height but lego version has high frame height due to space consuming lego transmission. Truck is still Renault Magnum look-alike but it has now better details, for example better cabin steps and handle bars. There are air wings and engine’s air intake behind cabin, which is now longer sleeper cabin with bed like real long haul trucks. There are also hoses behind cabin you can connect to trailer and other steps enabling to climb there to do this. Due to space consuming transmission there was no room for exhaust system or second fuel tank. All in all, this 4x2 tractor truck is very common Renault Magnum type, unlike my earlier 6x4 dump truck. And while this lego truck looks like Renault Magnum transmission is inspired by 12-speed version of ZF Ecosplit. B.2. This is how it is and could be done II:
This lego truck still has 12-speed transmission: 3-speed sequential main gearbox together with range-change unit and splitter. So technically this lego version doesn’t have much modifications while steering, main gearbox and range-change unit are same as earlier. But one driven axle is removed, frame shortened and splitter has new ratios 2,00 and 2,50 giving desired smaller gear step 1,25. While truck is now slightly slower it goes better in top gear when loaded. But two stage splitter wasn’t possible with this gear step so low split has four stages and only high split two stages. This splitter step 1,25 gives smaller step between two top gears and makes some progression in gear steps so transmission have better performance. Overall gear ratio is now slightly smaller 18,75 but thanks to progression it’s still typical for heavy duty trucks. Note: overall gear ratio is still high so be careful with lower gears that you don’t break gear wheels under high torque. And there is still same cheating part (24 teeth gear slides on the axle) in my truck, it’s coloured as light green in pictures. But this cheating part is not necessary if you modify also range-change unit. So, if you want build your own truck using this chassis available is alternative setup with standard lego parts. Again I offer only technic so you can use your imagination and design a truck you like. 12-speed 4x2 tractor truck can be DAF, Iveco, MAN, Mercedes, Renault, Scania, Volvo... at least. But let me see pictures if you make your own design. :-) Both original and alternative setup might be difficult to figure out from pictures so I recommend to download LDraw files. B.3. Semi trailer dump truck:
A tractor truck needs a semi trailer so I designed semi trailer dump truck. This kind of 4x2 truck with 3-axle semi trailer is common design in Central and Southern Europe. While this lego truck has high frame height trailer’s box is not horizontal when trailer is connected to truck. So there is semi-suspension in trailer: interaxle suspension allows axles to go up and down but in the axles left and right wheel goes up and down together. This axle group is a little bit complicated design but it allows to lift up front axle when unloaded so there is an extra lever inside trailer’s frame to enable that. Weight allocation is unequal: front axle takes 4/18 of axle group’s load while middle and rear axle take 7/18 each. This unequal arrangement is to give more weight on driven wheels when dumping load. I haven’t calculated weight allocation between truck and trailer. B.4. About semi trailer dump truck: Although this 4x2 truck and 3-axle semitrailer design is very common in Europe it works best in linehaul and on-highway purposes. There are several issues why it’s not very good design for dump truck use: When truck’s wheel base is short and 5th wheel located high reversing uphill will cause truck to “tilt” under trailer. This means that that extra weight coming from trailer goes over truck’s front wheels, not over driven wheels. So on rough terrains there will be wheel slip and you can’t reach difficult dumping areas. When dumping load there is not much weight on driven wheels so you can get stuck when moving off with box up. And while trailer’s box is longer than in dump trucks there can be stability problems during dumping on uneven ground. But many European countries have total weight limited to 40 tons and you need five axles to get maximum load. And most efficient 5-axle design is 4x2 truck with 3-axle semitrailer, better than 6x4 truck with 2-axle trailer or 10x4 truck. This is why 4x2 truck with 3-axle trailer is so popular in certain parts of Europe. When allowed total weight is higher you will need more axles to get maximum load. For example in Finland total weight is 76 tons with 9 axles, earlier it was 60 tons with 7 axles. This is when transfer dump truck using 8x4 or 10x4 truck and 4- or 5-axle full trailer comes most used and efficient design. [Back to main page] |
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