doug72

Its loosly based on a Hitachi CG70 tracked dump truck. I have added pphotos to my Flicka page. https://www.flickr.c...57650692142512/ Lego made a small "B" model 8294 which has a rotating body, i.e. cab and dump body rotate on the chassis togerther - manually operated. It would be a real challenge to sqeeze all the drives into a fully remote PF model. Need to order some more 5 x 11L yellow panels and connectors to make the dump body more uniform and a better shape. I made the model using parts I had available from older lego models. One problem has been matching yellow componants due "50 shades of yellow" from Lego over the years !!!!

Having built the 42030 Volvo Wheeled Loader and “B” model from spare parts I was not satisfied with the dump body not being able to hold anything due to the big gaps in the construction. Also disappointed with the dump body drive unit gear crunching when raising & lowering the dump body. Following the the theme on subtractor units I decided to strip the B model down and re-build as a Tracked Dump Truck using a subtracter drive unit to power it via a PF receiver. The dump body is raised and lowered by a PF switch operated by turning one of the a cab uprights. (the one with the black 12T bevel gear) The subtractor unit was made as compact as possible and it took three re-builds before I was satisfied with the chassis, track units and dump body unit. The subtractor unit has a XL motor which drive both tracks via a a two stage reduction of 4.66:1 - the steering is driven by an M motor to give slow turns when XL motor running or turns on the spot when M motor only running. Dump body is raised and lowered by an L motor via 3:1 reduction with a 24T clutch gear to protect the drive and has ample power to do this. PF Receiver / PF switch and battery box are hidden inside the engine housing next to the cab. battery switched on & off by the lever in front of drivers seat I build on a build it and see if it works / looks OK basis, if not rebuild. and try again it took several attempts before happy with the result, so no instructions. This is my first large MOC and pleased with the result. See photos on my Flicka page: https://www.flickr.c...57650692142512/

re Sled train: Its a Lombard log hauler for use on ice roads and could be either steam or diesel driven - in summer the front skids would be replaced by wheels

I have had some success in repairing crack parts using ABS liquid or super glues. Insert a axle into the part to open up the crack. Usings syringe or fine paint bush apply the glue to the crack. Immediately remove axle. Squeeze part together and allow to dry. Part now OK for light duties with friction hold resored.

I built the B model of 42030 from spare parts I had but didn't like it due to th "open" construction of the dump body. Tried in-filling with yellow foam board but didn't look right - so consinged to the spares boxes again. Now building MOC of a tracked dump truck - with track units & suspension based on the 8275 bulldozer. Tracks are driven is by a XL motor through a subtracter unit with an M motor for steering controled by PF RX Dump body raised / lowered by L motor - took awhile to get everything squeezed into the under carriage and to get pivot points correct without fouling the XL motor. Dump body will be operated by a PF switch disguised as the engine exhaust pipe ! Dump body built, with parts to hand but need to order more 5 x 11 yellow panels to complete. Next stage is to build the cab & engine bay sections. Sorry no photos or instructions as I am building it on a try it and see if it works and looks OK basis. Doug

Lego now have a trouble shooting page for train users - see:- http://service.lego....tery-box-issues Quote: The LEGO battery box works best with AAA batteries that provide 1.5 volts each. This is because the IR receiver and train motor require almost 9 volts (6x1.5V) in order to work properly. Rechargeable AAA batteries only provide 1.2 volts each, which is why we advise not to use them to power your train. Unquote: http://service.lego....052-city-trains

Although the rear diff. unit (with the small turntable) is built correctly as per instructions - it is quite easy for it to rotate 180 degs. as its joined to the the other section with red beams thus putting the diff. the wrong way round. I managed to do it as well. Front diff. unit cannot be assemble incorrectly if instructions are followed. Once chassis built it is best test every step before pocceeding.

I built a subtractor some time ago based on ideals in Sariel's excellent book "Unofficial Lego technic guide" It uses only two motors, the XL to run both tracks with a M motor when running slowing down one track for large radius turns. With XL motor stopped & M motor running the tracks run in opposite direction allowing turns on the spot. To avoid using small bevel gears I used knob gears for final transmission to the track drive wheels.

Quote: Also, using the Speed Controller with a Servo Motor sort of defeats the nifty auto-centre thing it does, but oh well. I learn the hard way. When using a servo with 7 step speed controller, to get back to CENTRE position quickly, no need to turn the speed dial, just press the RED stop button below the SPEED dial and it will self centre again.

The string around each pully is traverling at the same speed and as each pully is the same diameter there will be no slippage as long as the string is wound on in same direction of rotation - does not matter if they are loose are fixed on the same rotating shaft. Of more interest is the way the drag bucket is opererated when lifting a loaded loaded bucket. There must be some type of slip arrangement to keep tension on the drag rope to keep bucket in loaded position while the hoist rope raises it to the dump postion. The drag rope is then released and bucket tips down to empty it. I once saw a working 4mm scale model of a drag line excavator which had a very complex arrangement to operate the hoist and drag ropes in the correct sequence. The derricking sytem ( to move the boom) with its multiple pulleys is quite simple in comparison. I have been contemplating building a drag line excavator using the boom parts from the 7632 Lego Crane but have to work out the operating rope drives first.

A finger covering the IR Tx won't help - its blocking the IR link to the Rx.

Great mod to the steering and want to use it on the A and B models which now built. A model from 42030 set the hauler from spare parts. But can't open LDD file on my Mac OS 10.9.5 computer - can it be converted to a pdf file ?

What is the part number for the gray 2L pin with1L cross axle can't see it in the parts list ? Used at step 115 on page 187. Currently building the B model from parts to hand and have had to devise alterantive parts for some steps for the articulated hauler.

When I buy this I plan to use the Train controller for drive and steering which gives much smoother stop & starts, with a normal contoller for the other two functions. Did that with my Block Setting Crane for travel and slewing - more realistic.

In my Giant Block Setting Crane the battery box serves a dual use in providing the counter balance weight as well as powewring the PF componants. Maybe if crane was static an external suppy might be OK but if crane is mobile on rails trailing cables won't work.

The old Lego Control Centre had a very usefull function in that two memory programmes could be set up to allow models to run on auto. I,m glad I held onto mine as its has proved uesfull running old 9 volt motors and PF motors via adaptor cables. A similar device would be usefull for PF system control using IR link but without the large battery compartment. Could have 4 outputs each controlling a PF receiver i.e. 4 channels wth 8 outputs. Could be a lot cheaper than Mindstorm.

Good use of the Lego Control Centre (LCC). See my Transfer Crane which also uses the LCC http://www.flickr.co.../116189129@N03/ The two memory functions are great to have models run on auto. Hiding the wires is the only downside.

Mark 2 Crane:- As I wasn't happy with the first version - i.e. hoist trolley too big and drive arrangment not reliable. I rebuilt it to have both the hoist and trolley traverse drives within the cabin structure. This allows for a more compact hoist trollley. Main problem was gearing down the two 9 volt motors - this was done by a combination of drive belts and worm gears. Traverse motor has a half bush driving a wedge belt wheel which in turn drives a worm gear meshing with a 24T gear turning another wedge belt wheel around which the 1mm o.d. elasticated cord runs pulling the hoist trolly back and forth. Gear ratio 86.9:1 Hoist motor - same arrangment except worm meshes with a 12T double bevel gear connected to the hoist drum - gear ratio 43.3: 1 Hook is double purchase. The new drive set up is more compact, more realistic speed, more reliable and is protected from over travel by using rubber drive bands which allow motor half bush to slip if end travel reached. Now to find a way to hide the connecting wires ! New photos here:- http://www.flickr.co.../116189129@N03/

I,ve tried it on a spare PF motor but don't like the visual look so will keep with an 0-4-0 arrangement. Re mounting of Battery box - drilling a hole in the lower casing can be avoided if you use a 2 x 4 technic plate with holes over the pivot pin then place battery box on top - but raises everything by 1 plate.

Ashi, Thanks for info re middle wheel will give it a try on a spare motor I have. Found buffer / coulplings were one plate too low and have now raised to correct height. Alternative to drilling a hole in battery box base was to cut off the motor pivot but that would render it not usable later if used as a powered bogie. Also that end of the battery box would not be fixed. Not sure but old 9 volt motor without cable, I think the pivot plate could be removed making fitting battery box easier.

To use with my Ship to Rail transfer crane a small 0-4-0 dock shunter was needed. This uses a PF Train motor, AAA battery box and a PF Receiver. The aim was to make it as compact as possible - some slight mods needed to achieve this. PF train motor extended at each end by two 4 x 6 studded technic frames which clip into the locating points normally used for the buffer beam / couplings. Top of frame built up until level with studs on train motor and AA Battery box placed on top level with top of train motor. To achieve this a small hole was drilled through lower battery casing (through the centre ring between securing screw and casing end) to allow battery to sit on the train motor pivot pin thus securing that end - other end connects normally vis studs to the front 4 x 6 frame. PF receiver sits one brick behind battery box and is attached to rear 4 x 6 frame with a gap below to allow its PF cable to pass underneath. Both cables coiled up in the one brick space between battery box and PF reciever, the two side frames with doors helps to give more room for this. Body work built around AAA box and PF Rx. Yellow sticky back plastic film applied to battery box sides and colour is close match to lego bricks. I obtained the film from a road sign company. All studded surfaces covered with tiles. PF connector diguised as the engine exhaust. At first used decorative sides on the PF motor but they interferred with building the lower grey frame and were removed. Cab has a flat roof to allow loco to pass below my transfer crane and also the Block setting crane. I tried to add a centre wheel to make it a 0-6-0 but result failed. The engine is capable of pulling several wagons.

I'll post some photos of the dock shunter tomorrow - it was a tight sqeeze getting battery box, PF receiver plus connecting wires to fit out of sight. There is a new Lego store near me now so I am able to get any new parts I need.

JopieK: Crane is made from parts I had available and the hoist trolley housing had to be big enough to hold the reduction gears and the hoist drum. I might try and put the hoist winding drum in the green cabin structure as per my Block setting crane. Shunter is based around the PF 88000 AAA battery box with the yellow sticky back plastic applied to the sides. It is quite capable of hauling several wagons.

Having a Lego Technic Control centre and two 9 volt motors lying idle I decided to build a Transfer crane for my Lego loft layout. It uses studded lego technic beams and the legs from the 7939 crane, the legs are raisd to allow engines to pass underneath. Motor 1 drives the hoist trolley along the boom using a drive pulley and elasticated cord. Motor 2 drives the hoist drum inside the hoist trolley via 32L axle rod driving the worm gear and drum inside trolley housing. Hoist trolley runs along the top of smooth tiles. Both controled by the NS- EW control button on the Control unit. Biggest problem was fitting motors and gearing the drive into the Crane Cabin. The crane is static and does not move along the dockside. Small dockside shunter will form part of my planned layout with the Rail to Ship transfer carne and my Giant Block Setting Crane which can be viewed here:- http://www.flickr.co.../116189129@N03/

Crane now improved with boom tapered and rear housing extended by 2L so that battery box counter blances the boom better. Boom deflection less than 1mm when load on hook and hoist trolley at head of boom. Gear boxed now better braced and a 24T clutch gear added into the drive to the hoist trolley traversing to protect the 8T / worm gears. Mini Figure crane driver added !! Large PF controller - which gives better speed control - operates the under carriage travel and slewing of crane boom. Small PF controller operates, hoist trolley travel and hoist. Temporary Lego Train straight in use. Waiting on an order from Lego for more single track rails (3228) for crane to run on. New photos and video here: http://www.flickr.co.../116189129@N03/