doug72

Its something you put before a cart and will act as the steering direction indicator.

Thanks - have now added one (1) extra horse power ! Almost finished. Next task is to make a video, tying to guide it with a controller and record at the same time on a hand held camera.

Heavy Duty Differential: Now modified to allow for easy disassembly to replace the "questionable" method of removing the 2L axles from a 5x7 frame.. To support the axle knob gears either two 3L beams (white) or two LEGO Angle Connector #1 Red (32013) can be used instead of two #2 connectors. I will have to remove both wheels to change this. Now done using #1 connectors.

My first thoughts for a wacky wheel was to wrap a caterpillar track like yours but around a BWE gear ring using 3/4 pins in the tread link pin holes to locate it and then use a gear meshing with internal gear ring to rotate it, but it was not successful.

There are some good videos on YouTube about the Panjandrum including a modern replica. Thanks for your comment about my wheels - I too think its about the wackest wheel. I have even come across a square wheel for a bycycle but it requires a sinusoidal surface to roll along so bike does not bump up & down !!

Update: Rotating radar dish now added, it took a while to work out turning the drive through 2 x 90 degs in the space available to give slow rotation, drive is from L motor. Flashing warning light added: LEGO Light Brick with Transparent Top and Orange LED Light (62930 / 98785 installed on PF receiver and is activated by the driver rocking back and forth as the vehicle moves.

Panjandrum ? I hope you have better success than the original real machine.

Have a miniature control panel to fit - driver will operate this using a "thought control" helmet ! Already reached six functions - I mis-counted. L motor drives:- 1/. Wheels via a heavy duty differential. 2/. Dummy Vee 8 traverse engine with two flaming exhausts. 3/. Driver shaking up & down, also operates the flashing warning light. 4/. Two contra rotating drills. 5/. Rotating radar dish. Servo motor:- 6/. Rear steering 7/. Remote steering direction indicator at front of vehicle. Manual:- (still to be fitted) 8/. Crane for maintenence i.e changing worn out feet ! 9/. Small stores crane davit to bring supplies on board.

5th. wacky function now installed - only 999,995 to go ! A pair of forward facing contra rotating drills installed, powered from the differential turntable gear. The cyclist and pedestrian better run.

Can you have more than one extra wacky function ? I have 2 linked to drive & steering and have another idea for an independent driven function.

3rd wacky function = an occilating drivers cabin with a large Lego driver who is all shook up !! 4th wacky function = remote steering indicator added to front instead of the rear as the driver cannot see backwards !! Now tested and functions very smoothly with good steering capable of tight radius turns. Next step make a video.

Update: I was not really happy with limiting the servo travel mechanically, although power seems to shut off when it hits the stops. Now come up with a geared solution which works well and had advantage of placing servo in a horizontal position and increasing the overall length of the vehicle. Full travel of servo gives about 40 degs of turn for the steering wheels each way.
 An indicator is fitted so the driver can see which steering wheel are pointing. A dummy transverse Vee 8 engine has now been installed driven by the differential Z60 turntable.

Steering unit:- A servo motor best option and takes up minimal space. Used a pair of 4266 wheel hubs mounted below a turntable with tire destructors either side. Tested on living room carpet and steering function very well and differential comes into operation as vehicle turns. Only problem is when servo at full left or right at 90 degs the wheels drag. Will have to reduce the turning angle to about 45 degs each way using gearing. Also have to raise rear of frame by 1L to level it. New batteries installed and it now very fast & noisy as wheel rotates with clatter from the "feet" Will be controled using an 8879 speed controller. Problem !! If steering wheels go to full servo travel then they are at 90 degs to forward motion and drag. Tried restricting servo angular movement using gears but it then fails to centre properly due to gear teeth alignment. Next tried adding an idler gear in the the system to counter this but then too much backlash and again not centering properly. Solution: Revert to direct servo drive and add mechanical stops to limit the angular travel to about 45 degs each way. see red beams shown in photos.

Thanks Jim, makes a welcome change from four wheel super cars !

Should be no problem as don't intend to use it over a swamp or soft ground as the Tsar Tank did. Progress : I have decided to dispense with the chain drive & sprockets as they were causing too much friction making wheel rotation jerky. The support for the wheel axles was also causing them to lean outwards. Wheels are now directly driven by the differential unit. Wheels centres now re-built using a 3739 wheel hub which allows for six spokes to be attached. The wheel hub also has much less friction where it contacts the side frames and at the same time stops wheels leaning outwards. Wheel rotation now much improved and tire destructor devices added to wheel centres to combat other vehicles !! Next step is to build the steering unit using 1 of 2 possible solutions. 1/. Servo motor driving a gear or crank arm or 2/. Linear actuator moving a tiller arm. The rear steering unit probably use either a single wheel or 2 wheels close together. A dummy Vee 8 engine will be used driven somehow from drive uint.

The huge wheels were intended to cross significant obstacles. However, due to miscalculations of the weight, the rear wheel was prone to getting stuck in soft ground and ditches, and the front wheels were sometimes insufficient to pull it out. This led to a fiasco of tests before the high commission in August 1915. The tank remained in the location where it was tested, some 60 kilometres from Moscow until 1923 when it was finally taken apart for scrap.

No 2L axles were harmed during removal. A 2L axle with stop would be useful.

By using a sharp needle point you can prise them out far enough to grip with needle nose pliers.

Wondered who would be the first to spot that. They are fixed using 2L red axles and yes they can be removed quite easilly. 3L axles could be used if they don't foul other parts.

Progress : Heavy Duty Differential Ver. 1 Built using knob gears within a 5 x 7 frame and driven by a 60Z turntable.
 The other end of 5 x 7 frame supported by a 56Z turntable. The axle outputs have can have either 15T (blue) or 9T (Red) sprocket wheels to drive via chains the 21T (yellow) sprockets on the Boydell Wheels. Differential is driven by an M motor via double bevel gears to give 5:1 reduction.
 To prevent M motor fouling the Z60 turntable a 20T double bevel gear is used as an idler gear. i.e. 12 - 20 - 60 Result: too much friction in diff. and knob gears flexing occasionally causing one wheel to stall. Poor axle support causing Boydell wheels to bow outwards. Heavy Duty Differential Ver. 2 56Z turntable eliminated, support for knob gears improved along with improved axle support for drive outputs. Axle support for Boydell Wheels improved. L motor used for higher speed output with same 5:1 reduction and same chain drive to both wheels. Result : Improved and steadier rotation with much less friction and less bowing of wheels. I hope to keep the chain drive but will test wheel rotation without it. 21T yellow sprocket gears are used as they have a good arrangment of pin holes to allow wheel spokes to be at 90. degs.

There were several other types of “walking wheels” developed in the late 19th and early 20th centuries. 
The pedrail wheel is a type of wheel developed in the early 20th century for all-terrain locomotion. They consist of a series of "feet" (pedes in Latin) connected to pivots on a wheel. As the wheel turns, the feet come into contact with the ground, and rotate so they remain flat to the ground as the wheel moves over them. Pedrail wheels may be simple systems with the feet connected to a rigid wheel, but more complex systems including various built-in suspension systems were designed to improve performance on uneven ground. 
 L Difficult but not impossible to build using Lego. I chose the Boydell wheel as had enough parts to build it plus it used up un-used parts I obtained for my Bucket Chain Excavator, i.e chains & old style sprocket wheels. Currently developing a heavy duty differential as the standard Lego diffs are not strong enough and prone to the 12T single bevel gears failing under heavy load.

Here are bigger images:

The “Boydell Stomper” My “Wacky Wheels” vehicle is based on old technology that used a type of wheel invented by Boydell in 1846 which preceded caterpillar tracks in an attempt to allow heavy traction engines and artillery guns to cross soft ground and by the weirdest tank ever built, the experimental Russian Tsar Tank built in 1914 which was a complete failure !! Wheels now built:- Each wheel has a series of “feet” that spread the load. Each “foot” has a degree of movement allowing two feet to be in contact with the ground at at any one time, providing an endless track for the wheel to roll along. Can also climb shallow steps. My MOC will use a tricycle arrangement with two large diameter using “Boydell” wheels at the front with a smaller 3rd. wheel at the rear for steering. The two Boydell wheels will be chain driven by an XL motor via a differential. Steering will by servo motor moving the rear castor wheel as per the Tsar tank. Tried a subtractor unit for drive & steering but it was too weak and slow. The 3rd function will probably be a powered winch to help pull vehicle up steep slopes if required or by using shear legs be able to lift objects such as other “Wacky Wheels”. Next step is to build the frame to house motors etc. plus a drivers control cabin.

Excellent build of the Mark V tank. There were two types Male as per your model and Females which only had machine guns. The Bovington Tank Museum in Dorset, England may be able to answer your query re max. climbing angle. The museum has a huge collection of tanks - some in working order and used in displays. http://www.tankmuseum.org

Thanks, my wheels will really wack the ground !