Indispensable Around the Homestead

We continue the story of the machines and mechanisms built by V. A. SVERBL — an amateur designer from the village of Zelenchukskaya in the Karachay-Cherkess Republic. In the publications “Walk-behind tractor — nothing superfluous”, “A reliable helper for the walk-behind tractor” and “A compact car with the character of an all-terrain vehicle” (“Modelist-Konstruktor” Nos. 2, 3 and 4 for 1998), his “Elektronik” walk-behind tractor, cargo trailer and jeep-style car are described. This time the subject is the design of the “Shassik” mini-tractor.

V. A. Sverbl built the mini-tractor at the request of his older brother. The brother had started a major house renovation and hoped to use the “Elektronik” with a trailer to deliver building materials. However, Vasily Alekseyevich could not spare the walk-behind tractor for long — his own and the neighbors’ vegetable gardens would not wait — so he decided to “quickly” make something that could haul loads, turn around literally on a dime (his brother’s yard was not all that large), and at the same time till the garden. A tractor of the “self-propelled chassis” layout suited this role perfectly. Hence, incidentally, its name — “Shassik”.

The new vehicle was built, like everything Sverbl Jr. took on, very quickly. Literally a week later a blue-painted mini-tractor rolled up to the yard of Sverbl Sr.; as soon became clear, it could carry up to half a ton of cargo at up to 50 km/h and turn around on a pad with a radius of 3.5 m.

“Shassik” was assembled, as they say, from whatever was available. It uses a great deal of what fills the garages and sheds of self-respecting DIY builders. In this case the designer took the engine with gearbox, starter, generator, fuel tank (18 L capacity), steering gear and brake-system units from an S3D motorized carriage; the final drive from a “Muravey” cargo scooter; the propeller shafts from a GAZ-51 truck; on the front axle he fitted the rear wheels with hubs and brakes from the same motorized carriage, and on the rear drive axle — the front wheels with final-drive reduction gears from a T-40 tractor. The battery for the 12 V onboard electrical system came from a “Zhiguli”, the windshield-wiper motor and blade from a GAZ-69, and the remaining electrical equipment from other machines and mechanisms.

Using ready-made units and assemblies made it possible to reduce the number of homemade structural parts to a minimum and thereby substantially shorten the time needed to build the mini-tractor.

Here are those homemade parts.

FRAME. It is a simple truss welded mainly from angle stock of various sections. Despite the large number of parts, the frame is fairly easy to make. The truss design is shown in the drawing and therefore needs no detailed description. Just a word about the fact that the side-reduction-gear brackets have lugs for attaching a hitch bar for implements — a strong thick-walled pipe that can tow a plow, a harrow, or a drag.

CAB. The climate of Karachay-Cherkessia is difficult, and the weather in the foothills is unpredictable. Therefore the mini-tractor cab was designed so that one could work in it at any time of year — including winter, because warm air from the engine under the driver’s seat heats it well. The walls did not even need to be insulated.

On a hot day the cab is easily ventilated; for this purpose it has a rear transom that opens upward.

The driver’s workstation is equipped with everything needed for full control of the mini-tractor: a steering wheel, clutch, throttle and brake pedals (its hydraulic actuator acts only on the front wheels), gearshift, reverse and parking-brake levers (its mechanical actuator also acts only on the front wheels), and an instrument cluster for monitoring the engine and onboard systems.

CARGO BODY. Its dimensions are modest, yet, as Vasily Alekseyevich put it, it holds “forty buckets and two more sacks of potatoes on top”.

The body is made of knot-free pine boards 30 mm thick, lined on the floor with steel sheet and reinforced on the sides with steel angles. The front and side boards are hinged, which makes loading and unloading easier. The body is still unloaded by hand for now, although provision is made for mechanical tipping with a power hydraulic drive.

Space on the frame is even reserved for a hydraulic pump and a hydraulic cylinder: the former is located behind the battery, and the latter is pivot-mounted in the lugs of the matching support. Its rod bears against the geometric center of the floor, located behind the axis about which the body pivots when raised. This kinematics simplified the body design and eliminated the need to lock it against self-tipping. However, for lack of time Vasily Alekseyevich left the engine modification for driving the hydraulic system for later.

FRONT AXLE. It is a lever-type design with one degree of freedom. It is made of several lengths of thick-walled steel tube and is attached to the front of the frame by a sturdy pivot. The kingpin bushings are also made of steel tube and contain bronze plain bearings and kingpins, to the bottoms of which are welded hub brackets cut from the swing arms of an S3D motorized-carriage rear axle. Steering pitman arms and plate-type fender mounting lugs are bolted to the tops of the kingpins.

Here it is worth describing a small modification of the motorized carriage’s steering. An additional pivot assembly (the stator belongs to the frame, the rotor to the steering rocker) and the rocker itself were added to the stock set of parts. Owing to its rather complex shape, it introduces nonlinearity into the wheel-turning process, causing the inner wheel to deflect through a larger angle, which improves the mini-tractor’s maneuverability.

MUFFLER. It is assembled from lengths of pipe of various diameters. The inlet stubs are stock ones from the motorized carriage. On the mini-tractor the muffler is attached by two stock bracket clamps to the engine mount and connected to its exhaust pipes.

A few words about the “Shassik” transmission. As already noted, the designer took the final drive from a “Muravey” cargo scooter and mounted it in the stock engine-mount brackets. He then connected the outer yokes of the flexible drive joints to the forks of the rear-wheel final-drive reduction gears with half-axles — shortened GAZ-51 propeller shafts.

It would be wrong to claim that “Shassik” has no shortcomings. Like any homemade machine, it is far from ideal. Its virtue lies elsewhere. It is a clear example of a creative approach to reality. From seemingly scrap materials and worn-out parts, a rural designer built a mini-tractor that helps him solve many household problems. Such an attitude deserves both respect and imitation.

“Modelist-Konstruktor” No. 5’98, A. TIMCHENKO