The 8828 loader, released in 1992, is the smaller cousin of the previous 8853 - Excavator. It has the same features, but implements them in a different way. It features rear wheel rack and pinion steering and a scoop which lifts and dumps via flex cables. Despite its compact size, its appearance is quite accurate and the functions work great.
This is the first set to use the new smaller black bucket which would remain in use for a long time. Other than that, it does not really break any new ground.
The rear wheels can be steered using an overhead "Hand of God" control.
The overhead control drives an axle connected to a pair of 14 tooth bevel gears. The second axle drives a rack via an 8 tooth pinion gear. The steering mechanism itself uses steering arms and toothed links as shown in the computer image. Note that the steering arms actually point backward in this case.
The front bucket can be lifted via a crank on the left side of the vehicle. The crank is made from an engine crankshaft part. The crank turns a worm gear which drives a 24 tooth crown. Next a set of 14 tooth bevel gears rotate a liftarm. The liftarms make up one leg of a 4 bar linkage which then raises the bucket.
The use of a worm gear results in a system which cannot be backdriven (because the axial friction is higher than the backdriving torque due to the screw pitch angle) which allows the bucket to be supported so that it does not fall under its own weight.
The front bucket can be dumped via a crank on the right side of the vehicle. The crank is made from an engine crankshaft part which rotates another pair of crankshaft parts. The 1/2 stud offset of these parts allows a total "stroke" of 1 stud. The crank pin drives a pair of flex cables which connect to a vertical linkage. The top of the vertical linkage connects to a horizontal link which terminates at the bucket's upper lugs. Translation of the link causes rotation of the bucket about the lower lugs.
If you look carefully at the animation, you can see that the crank goes over center when the bucket is up which locks it in place and prevents it from tipping.
Although I'm always happy to see the flex system used, in this case it is kind of pointless. The cables do not negotiate any curves so the same function could have been easily accomplished with rigid links.
This set uses four of the smaller size foam 20x30 tires and wheels. Keen eyed observers may note that my set actually has rubber tires, but this is not historically accurate, it is just what my second hand set happened to come with. This was the last set to use these foam tires. Their replacement would look nearly identical but be made of rubber.
By Technicopedia