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Freightliner M2

May 25, 2012 1 Comment

For some reason, I often find myself building two trial trucks at the same time. While I was building my ZIL 132, I also wanted to try something with floating axles. The model would use 6 wheels, a 3 speed transmission, and fully suspended live axles. I also wanted to model the Freightliner M2 Business Class truck as closely as I could.

The model started as my trucks usually do; with the axles. The second and third axles would be identical, and would be connected with a simple pulley wheel universal joint between the two. To keep the speed through the universal joints high, and the torque low, I used as 12z/20z gearing after the universal joints, then the knob wheels to rotate the axis, then the normal 8z/24z gearing on the portal axles to finalize the drive. This also allowed me to keep fewer knob wheels as the second axle had the drive shaft from the transmission pass uninterrupted to the rear wheels. The final drive ratio for the two rear axles were 1:5.

The front axle was a little more work. I wanted to have the steering motor mounted on the axle so I would not need to have a steering shaft connect to the front axle. This proved too difficult, as it would raise the PF XL motor that I was going to use for the drive to high on the truck. I decided it would be better to mount the steering motor on the frame and connect to the front axle via a CV joint. Once I made this decision, the front axle became easier. I used a 1:3 gearing on the portal axles, a knob wheel, and then a drive shaft back to the transmission. The steering axle would exit just above the drive shaft on the axle to move to the right for the steering motor.

The frame was pretty simple. Once I had the transmission placed, and the axles spaced, it was simple to place the suspension components, and the shock absorbers. Each axle had two steering links mounted vertically which connected to a 3×5 liftarm which would activate a shock absorber; very much like Lyyar’s design. Each axle had a steering arm to keep the axle from swaying laterally. Finally, all three axles had a number of 9L links to keep the various movements maintained.

The transmission was going to be placed behind the PF XL motor which was under the hood. The changeover mechanissm would be placed in the center of the truck with the changeover motors mounted longitudinally, on both sides of the truck. The PF XL motor was place directly above the first axle, and was mounted on a moving frame that was moved by the changeover. This allowed a moving frame to work its way through the three gears. The ratios were 1.25:1, 1:1.25, and 1:2. This allowed for final ratios of 1:4, 1:6.25, and 1:10, which was more than capable for most terrain. The drive and steering Battery Box was mounted over the second and third axles, and the gearbox 8878 battery box was just behind the changeover in a little box on the bed of the truck.

Finally, like always, a simple body was mounted. I had a little trouble getting the look I wanted on the front of the hood, as the suspension components kept getting in the way. I added a bed, covered the changeover and motors, and a couple more details and everything was finished.

The model was not my best driving truck, as six axles do not want to always work together. The suspensions was supple, and I was getting no drive or steering input on the suspension. The truck worked well over various terrain, but struggled on some on step obstacles. The transmission mounting worked well at changing gears, but gears did not have a strong support, and I found they liked to skip at times. I liked how the suspension worked, but I do not think it brought enough of a valued to use this system again. It had moderate improvement on dealing with terrain, but it placed a lot of stress on a number of parts, such as the frame, the axles, the driveshafts, and the universal joints. The next truck will use a pendular set up again.

The full gallery may be found here.

Filed under Trial Truck Tagged with 8878, Gearbox, live axle, MOC, PF M, PF XL, portal axles, power functions, remote control, steering, suspension, technic, trial truck, visorak

Power Functions 4×4 8081

May 18, 2012 9 Comments

For most LEGO enthusists, when they purchased the set 8081, they quickly modified the set with a Power Functions drivetrain. It makes sense. LEGO models are a little more exciting when they are motorized. But I guess I went a little backwards. I wanted to do the fun stuff first, and make the most complicated and compact drivetrain I could make. I posted the instructions here, and they can also be viewed on Rebrickable.com.

But the comments kept coming from people who wanted to see my model motorized. So I thought it might be a fun addition. I added a two PF M motors, a 8878 Battary Box, and an IR receiver. I tried to keep the modifications simple, so I could easily add the motors to the MOD, and take the system out if I wanted to. The drive motor was placed on a simple mount that connected to the frame. The power was fed thought a 8z gear to a 24z gear which then connected directly to the V8 driveshaft. The driveline was unchanged from the V8 down. The steering motor was mounted laterally in front of the rear seats. A 20z double bevel gear drove a 16z gear, then a worm gear moved the final 8z gear which was mounted on the existing HOG steering axle. I removed the passanger seat which is where I placed the battary box, and created a simple mount for the IR receiver. The added weight required a new shock absorber, so I added that as well.

The model worked alright. The drivetrain did well to handle the new power, and I could easily control the Crusier. The steering motor was a little too powerful for the upside down facing steering rack. It skipped a little under load, which was a problem over rougher terrain. The drive motor was a little taxed, so a PF XL would have done a little better. I guess I could add that, but I am ready to move on to my next model. Stay tuned.

The full gallery may be found here.

Filed under MODs Tagged with 8081, 8878, Cylinder, Differential, Instructions, live axle, MOD, Panhard, PF M, power functions, remote control, steering, suspension, technic, V-8, Worm Gear

Zil 132

May 4, 2012 4 Comments

A couple of months ago I was struck by a new design by Waler. It was refreshing to see a well made Trial Truck based on something a little different. I wanted to make a model of my own. Thanks to him for the inspiration, and for the great ideas on the cab and the fenders.

From the beginning I knew this truck was not going to be a serious off road contender, but I wanted to redesign the whole drivetrain. I decided to go with a pendular suspension for the first and second axle and a trailing live axle for the third axle. All three axles would have a differential and a a set of portal axles. The first and the third axle would also have steering linked together. As is often the case with my trucks, I had the pendular axles held by a turntable with the steering function passed through the turntable by use of a differential. The second axle was held by a turntable in the front, and the steering differential passed through to provide steering to the final axle. The drive function powered all three axles and would connect to the transmission and motor in between the first and second axle.

The third axle was a suspended live axle that had a trailing setup created with the new 8110 pieces. This would allow for rotational and vertical articulation while connecting the drive shaft and giving space to the steering function above. The steering shaft would allow for movement via a CV joint. The Power Functions M steering motor was placed in the rear, and used a simple 1:9 reduction.

A Power Functions XL was used for the drive funtion and was placed between the front two seats. The motor was mounted on a sliding assembly for the gearbox function, much like the design pioneered by ATRX. I used my three speed changeover design to move the motor through three gears, for a final ration of 1:7.5, 1:4.7, and 1:3. The gearshift worked perfectly. While the drivetrain was a little complicated, the gearing was rather simple. The battery boxes were place above the second axle side by side. This kept the weight centered, and as low as I could get it.

Finally I added a cabin and a cargo area. The cabin was straight from Waler’s design, as was much of the fender area. I used technic panels to create the cargo area, which also gave me a space to place the two IR receivers. This also hid the two battery boxes, and the wiring, and generally cleaned up the truck. I created two small doors in the top to assist with picking up the ZIL. I was done.

Over mostly level ground the ZIL was one of my better designs. The differentials and steering worked flawlessly to make the ZIL drive easily. The gearbox worked well and eased the drivetrain over slight irregularities. But once the pavement turned to dirt the ZIL struggled a little more. It was not designed to have too much suspension travel, and this showed. It struggled on some of the bigger bumps, as the tires would scrape the wheel-wells. Overall, I was pleased with the design, and was happy with the way it turned out. It looked great, it was fun to build, and it was a blast to drive.

The full gallery can be viewed here. Also, a big thank you to The Lego Car Blog for posting this model on their blog.

Filed under Trial Truck Tagged with Differential, Driveline, Gearbox, live axle, MOC, PF M, PF XL, portal axles, power functions, remote control, steering, suspension, technic, trial truck, visorak

Mercedes Benz Axor Refuse

May 1, 2012 2 Comments

I am a big fan of garbage trucks. For some reason I find the combination of a smaller truck,with many features all with a complicated compaction device is a great basis for a complicated LEGO Technic model. Plus, trucks are fun.

The hardest part was going to be the rear compaction device, so that is where I started. I decided to use a Geesink Norba design as it would give me the largest opening for the trash in the rear because the mechanicals would be on the bottom on and the top of the opening. 13 studs wide is not much space. In addition, this would allow me to have the rear hopper pivot up to let the trash out when it was full. I would need to have three functions going though the pivoting hopper. One at the pivot, and two connecting at the base when the hopper was closed.

The dumpster lift would be driven through a knob gear when the hopper was closed on the bottom. The compation device would be operated with a gear on the bottom and a mini linear actuator on the top. This mini linear actuator would also function as the opener for the rear compactor. All the motors would be housed on the bottom, with one motor placed next to thebattery box. The extractor would be operated by another mini linear actuator using a scissors mechanism to move the ejector plate.

The chassis was constructed with a PF XL in front of the steering axle. The motor would power both the drive, and the extractor changed by a changeover. The steering motor is placed on the right of the truck. On the left, another PF M motor powers both the dumpster lift and the lower hopper compaction device. All power came from a 8878 rechargeable battery box, through two PF IR receivers, and powered four motors: One XL for drive and the extraction plate, one M for steering, one M for the dumpster lift and lower compaction, and one M for upper extraction and hopper opening.

The model worked well, particularly steering and the drive. However the extraction and the hopper opening was a little less reliable. The hopper was too heavy for a single mini linear actuator, and the compaction device was not stiff enough. It happened to get caught on some of the internal edges on the inside of the hopper. The next garbage truck will need to be built a little more sturdy.

The full gallery may be seen here.

Filed under Construction Tagged with 8878, Axor, Differential, Driveline, Garbage, Geesink Norba, Mercedes Benz, mLA, MOC, PF M, PF XL, power functions, Refuse, remote control, steering, technic, Worm Gear

Kenworth T55

April 28, 2012 8 Comments

Traction. It’s all about traction when designing a trial truck. Because of this, many builders have tried a number of different solutions in designing their own trucks: differentials, gearboxes, various numbers of wheels, various gears ratios, countless suspension designs, and on and on. So why would it be any different for my trucks? Every truck I make is a reaction to some set of problems I have encountered with a previous truck. This is my current solution.

The full gallery is here. Instructions are here.

The Kenworth T55 started as a proof of concept, and turned into a design of a fictional truck. I wanted to somehow see if there was a way to use differentials in a successful trial truck. For this to work, two things had to be accomplished. First, there had to be a way to keep the tires from spinning uncontrollably when they lost contact with the ground. And second, the torque going through the differential had to be low enough that it would not shred the gears inside the differential when the truck encountered an obstacle. Could I make axles that had a limited slip differential while having all of the gear reduction at the hub?

Enter turntables. I have seen some ideas before, most sigificantly from Borec, including this truck, so I went to work. I designed a mount for the wheels and tires, and placed the universal joint as close the wheels as I could. Then I used a limited slip differentail design, and sent the driveshaft back to the body. A simple steering design was used, and the two fuctions passed through the common design of using a differental body through a turntable.

The chassis was designed to keep the weight low, both is mass and location. As is common, I used the Power Functions XL motor for drive, and I decided to use the 8878 Battery box as it was significally lighter than the other design. In addition, I would have a drive shaft and a steering shaft running the length of the truck, so the motor and power pack needed to set on both sided of the truck. Also, because I used the turntables, the drive shaft was very high. This gave great ground clearance, but I needed to keep the heavy components low. By having both large components on the side, I was able to keep a short wheelbase of 30 studs, and keep the mass centered and low. The driveline was complete.

Ever since my GMC 2500, I have held to the belief that a linked suspension is the most efective setup for four wheel trial trucks. The design keeps all four wheels firmly planned, and does not have the wobbling feel of many pendular suspension designs. But as is often the case, I ran out of room to place a link rod between the two wheels so I opted with useing the rubber connectors to keep the axles level. I added a body, and a steering motor, wired everything together, and I was done.

So how did it work. As you can see in the video, the suspension was effected by the steering and drive shafts. This further confirms my thoughts on the linked suspension. Second, the turntables did not really add much. They added a lot of friction to the driveline, and though they kept the differentials safe because of the tall final gear they did not really isolate the forces on the differential as much as I would have liked. Third, the limited slip differentials worked well, but still allowed for too much wheel slip. I ended up replacing the rear with a locked axle, which seemed to work well. So, for the next truck, bring back the linked suspension, and find a better differential solution. Maybe then I can find some more traction.

Filed under Trial Truck Tagged with 8878, Differential, Driveline, Instructions, Limited Slip, PF M, PF XL, portal axles, power functions, remote control, steering, suspension, trial truck, Turntable, visorak

4×4 8081

April 26, 2012 9 Comments

Truthfully, I was excited about set 8081 when it was first announced. I liked the size. I liked the coloring. I liked the stance. But mostly I liked the potential. Most of the Technic community dismissed the 8081 because of its watered down functions, but I was interested in making some changes to see if I could make the Cruiser Extreme.

The full gallery can be found here, and instructions here.

I first added a V-8. There was plenty of room, and after seeing a great modification from Efferman, I had some ideas. It was a simple addition.

Next was the drivetrain. This was a little more complicated. I wanted to make it four wheel drive, and I wanted to make sure there were three differentials. I rebuilt the rear axle, so It would have a more active setup. I put in longer shocks, and added a Panhard rod, and two stabilizing links. It worked well. The front axle was more challenging. The new CV joints made the project a little easier. Once I had the differential place, I had to fit everything around it. The steering rack was placed upside down, and was connected directly to the existing steering link in the original 8081. Then I added a Panhard rod on the front of the axle, and rebuild the front bumper, and everything was set.

Instructions can be found at Rebrickable.com or here.

Full gallery is here.

I also created a motorized version after a number of requests. You may see the gallery for that MOD here.

Filed under MODs Tagged with 2012, 8081, 8878, Instructions, live axle, MOD, Panhard, PF M, power functions, steering, suspension, technic

LMTV Mini Truck Trial

April 21, 2012 Leave a comment

As I start this new blog, I thought it may be helpful to post some of my older models to show what I have done, and give a little history to my designs. In the midst of getting into Trial Trucks, I decided it was time to make a new smaller truck. I designed a mini truck, to test my abilities with smaller functions based on the Oshkosh LMTV military truck, and to take my mind off the design that was taking most of my time.

I chose the six wheel truck as it would make the suspension of the truck a little more simple than other designs. The rear axles would be tied together on each side, with a pivot point in between each wheel; one for each side. A single axle would connect both sides through the dual pivot points, and would be powered by a worm gear directly from the drive motor. This set-up did not require any additional suspension components, and this would allow the front axle to use an unsuspended pendular set up. The PF M drive motor was placed above the rear wheels and drove an axle that would go to both the front and rear axles.

Like the rear, the front axle would use a worm gear directly from the motor to drive the wheels. From the worm gear, a 8z gear was used to drive two 12z double bevel gears for each wheel. Both 12z gears would drive two more 12z double bevel gears to which allowed for drive through the steering axis. A simple link connected the two steering wheels, and used a rack and pinion setup to transmit the steering function. It worked well, and allowed the steering motor to slip at steering lock. A PF M steering motor was placed above the front axle in the cabin.

I created a small bed, and cabin for the truck and decided to build the truck in blue. As I was browsing through my Brickshelf folder, I noticed I had too many red vehicles, so something blue would be good. I placed the 8878 battery box, and PF receiver between the cab and the bed. This allowed for proper center of mass, and gave me a fully functioning bed.

The model worked well. For such a small vehicle, it took a lot to stop the truck, in part because of the worm gears. The steering worked well, but the turning radius was limited, due to the poor steering lock. I was a fun model, and it is still one of my more popular projects on Flickr. See the full brickshelf gallery for a more complete view.

Filed under Trial Truck Tagged with 2010, 8878, MOC, PF M, power functions, remote control, steering, suspension, technic, trial truck, Worm Gear

T-72

April 17, 2012 6 Comments

As a child I always wanted a model of the Russian T-72, so I decided to create a version of the tank out of LEGO bricks. As is often the case, the model started with wheels. This determined the scale, and from there, I was able to determine the rest of the tank dimensions. This gave me very little room for all the functions of the tank.

Instructions are available for $5 USD.

Model of the popular Russian T-72. View the full gallery here.

: Suspension of the tank.

The tank includes independent suspension on all 12 of the drive wheels. 6 are suspended with 6.5 length shock absorbers, 4 are suspended with rubber connectors, and the final two are not suspended, but move freely with the track. The tracks are driven from the rear by two longitudinally mounted PF M motors. These are connected 1:1, through double bevel gears to the 24z sprockets. The battery box is place in the front of the tank, with the IR receivers placed over the drive motors. The final PF M is mounted vertically in the turntable, to rotate the turret. It could use another reduction, as the rotation is a little quick as you can see below.