Thursday, 5 May 2016

Unimog Attachment - Flail Mower

Over the past couple of weeks I have been researching, designing and building another LEGO Technic Unimog attachment, this is a flail mower. A few years ago I watched my local council mowing along a creek using one of these and thought it would make a good attachment, it is only now that I have the right pieces to make it possible. 

For those who don't know what a flail mower is, below in red is some information from Wikipedia.

"Flail mower - From Wikipedia, the free encyclopedia

A flail mower is a type of powered garden/agricultural equipment, which is used to deal with heavier grass/scrub which a normal lawn mower could not cope with. Some smaller models are self-powered, but many are PTO driven implements, which can attach to the three-point hitches found on the rear of most tractors. This type of mower is best used to provide a rough cut to taller grass where contact with loose debris may be possible such as roadsides.

The flail mower gets its name from the use of "flails" attached to its rotating horizontal drum (also called tube, rotor, or axle). Many implement companies also refer to the flails as knives or blades. The rows of flails are usually staggered to provide a complete cut. The flails are attached to the drum using chain links or brackets, depending on the manufacturer. The rotating drum is perpendicular to the axis of the tractor. The PTO driveshaft along the tractor's axis must make a right angle through the use of a gearbox in order to transfer its rotational energy to the drum. As the drum rotates, centrifugal force pushes the flails outward.[1]

Standard flails are shaped like an extruded "T" or "Y" and the chain attaches to the bottom. There are also proprietary flails with different shapes for shredding larger brush and others that leave a smooth, finish cut.

If a flail strikes an immovable object, it simply bounces off. Other rotary type mowers have a tendency to grab and throw the object out of the mower deck if its small enough. This fact makes the flail mower best suited for areas where thrown objects would cause damage.

Flail mowers may also be used in a more or less upright position for trimming the sides of hedges. They are often called hedge cutters (or sometimes also hedge trimmers) then. Especially in forestry (agroforestry) some very robust variants of flail mowers – called flail mulchers, flail shredders, or flail choppers – are used."

Over the past couple of weeks I have been researching, designing and building this. I wanted this to have two features, the lifting of the how mowing attachment and the turning of the flails, to do this using just the single front PTO I have built a two way switch box, this allows both functions to work off a single PTO. Most of my time working on this has been on the mowing part, getting the gearing right and adjusting the height to ensure it is low enough to mow without hitting the ground too much.

Overall I am very happy with how this has turned out, it works as I want it to and is something a bit different. It is also another "front" attachment which is something I have not built many of and brings with it a number of design and construction challenges which are different to those faced when building "rear" attachments.

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