42065 RC Tracked Racer, IR Remote



The new RC Tracked Racer is currently the only way to obtain the Lego infrared (IR) transmitter/reciever remote control in shops. I picked it up yesterday as it’s been released long enough to be discounted.

It’s quite a nice design, the battery box is mounted low and centrally. Each track is driven by it’s own medium motor, one mounted forward and the other rearward. The car body flips forwards to allow good access to the battery box switch.
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8066 Off-Roader


This is set 8066 Off-Roader, purchased as a set off eBay. It’s a small (143 parts) Technic set.

steering detailAs I built it, I was concerned the steering would have a large hysteresis as the fit between the two pins that transfer the rotation to the steering have a large clearance. In practice this is not an issue, it’s a particularly nice steerer.

You’d expect an “Off Roader” to have a long travel suspension, which this does. The vehicle has a pivot point near it’s centre of gravity and the front and back swingarms and chassis all meet here. The suspension is a mono spring/shock absorber across this pivot point. This is a common approach in real vehicles, but in this design, the axles are not floating so the Off Roader has great bouncy suspension front to back, but is solid side to side.

pivot pointOne nice Technic design aspect is the universal joint in the steering linkage. The steering is controlled from a gear at the back, so the linkage needs to transfer the rotation across the pivot point. This is accomplished by adding a universal joint at the pivot point – a common engineering solution to similar real world problems. In the picture here I’ve added a green line to show the axis of rotation the suspension is moving around and removed the left seat to expose the universal joint.