What is the mini-tractor “Muravey” like? What lies behind its pleasing, eye-catching forms?
Indeed, the kinematics here fit the designer’s concept perfectly. The engine is a single-cylinder, two-stroke, air-cooled unit rated at 14 hp. It was taken from the Tula-200 motor scooter. The clutch is multi-disc, running in an oil bath.
The tractor is fitted with two mechanical gearboxes. The rear axle is lockable and has a demultiplier. The kinematic layout makes maximum use of industrial parts and assemblies. For example, sprocket Z2=38 comes from the Tourist motor scooter (rear), as does the PR-12.7 chain. Sprockets Z1, Z3—Z6 and the PR 19.05 chain were taken from scrapped agricultural machinery. Sprocket Z6 on the power take-off shaft is removable; if necessary, a lathe chuck drive or similar can be installed in its place. Z7 was also taken from scrapped agricultural machinery and welded in place of the flange on the GAZ-69 transfer case.
1 — turn signal, 2 — headlight, 3 — hood, 4 — engine, 5 — air filter, 6 — clutch pedal, 7 — gearshift lever, 8 — steering column, 9 — high-speed gear lever, 10 — rear fender, 11 — seat, 12 — suspension drive lever, 13 — rear light, 14 — suspension, 15 — rear wheel, 16 — steering wheel, 17 — reflector, 18 — decorative grille, 19 — bumper, 20 — tie rod, 21 — front wheel, 22 — tow hook, 23 — front fender, 24 — mud flap, 25 — brake pedal, 26 — footboard, 27 — throttle pedal, 28 — reverse lever, 29 — demultiplier lever, 30 — rear wheel lock lever, 31 — brake light and turn signals, 32 — power take-off shaft cover, 33 — muffler.
1 — steered (front) wheels, 2 — Tula-200 engine, 3 — GAZ-21 gearbox, 4 — removable power take-off sprocket on the intermediate shaft, 5 — GAZ-69 transfer case with brake drum and wheel lock unit, 6 — driving (rear) wheels.
The use of the GAZ-69 transfer case in the Muravey design is no accident. It allows wheel locking and has a reduction gear. Most importantly, it has a brake drum with factory-made shoes capable of providing reliable braking for the mini-tractor both on the move and at a standstill.
1 — driving wheel half-shaft (GAZ-69 driveshaft shortened to 350 mm), 2 — top of the box section of the frame, 3 — self-aligning bearings with tension bushings (from the Niva combine straw walker) No. 1680206S17, 4 — bracket (75X75 mm angle welded to the top of the box section of the frame), 5 — wheel disc, 6 — flange with hub welded to the wheel disc, 7 — washer, 8 — M25 nut, 9 — flat, 10 — M10 bolt.
Rotation from the transfer case is transmitted to the driving wheel half-shafts made from GAZ-69 driveshafts. Each half-shaft is mounted underneath on the box section of the frame structure, reinforced with a 75X75 mm angle, using two self-centering bearings No. 1680206S17 placed together (between the universal joint and the flange mounted on the end of the axle). The same bearings, taken from a scrapped Niva combine straw walker, are also used to mount the power take-off shaft (on top of the side members, at the box section of the frame structure).
1 — front axle bushing, 2 — cross beam reinforced with stiffening ribs, 3 — front wheel axle upright, 4 — “cup” for mounting the front fender bracket, 5 — M6 screw, 6 — M27 round nuts (4 pcs.), 7 — left wheel axle welded to the upright shaft and the swivel arm, 8 — right wheel axle welded to the upright shaft and the steering linkage arm.
As driving wheels (considering their availability, which nowadays is an important factor), 5.50-16 inch wheels from L-182 agricultural machines were used. For mounting them, it is advisable to use a method well known to all enthusiasts who build automotive and motorcycle vehicles. A flat — a machined flat on the shaft — should be made by slightly turning down the end of the shaft. In this case, the flat should preferably be made on the section from the M25 thread, where the flat reaches a width of 20 mm, and then for 45 mm along the shaft with a taper to nothing. The wheel disc is welded around the circumference to a 15 mm thick flange with a 30 mm hub; on its inner diameter there is a protrusion similar to the flat on the shaft. The wheel is fitted onto the half-shaft prepared in this way and tightened with an M25 nut and a 10 mm thick washer.
1 — steering wheel, 2 — steering shaft, 3 — universal joint, 4 — steering mechanism, 5 — swivel arm, 6 — pitman arm, 7 — tie rod, 8 — tie rod end GAZ-69 (GAZ-21), 9 — steering linkage arm, 10 — front wheel axle upright, 11 — steered (front) wheel.
A good mini-tractor must have steering that is easy to use and reliable in operation. On the Muravey, the front axle beam is homemade, made from thick-walled pipe reinforced with welded stiffening ribs. The steering mechanism parts were borrowed from the Moskvich-400 car. The front wheel axle uprights are mounted on thrust ball bearings, which makes wheel turning easy. On top of each upright there is a “cup” with a welded front fender bracket and a mounting hole in which an M6 screw thread is cut. The Muravey’s front wheels come from the Tula-200 motor scooter (model K-82: 4.00—10 inches). The steering shaft (overall length 1200 mm) is from the GAZ-51.
1 — side member (100×80 channel), 2 — front cross member (100X80 channel), 3 — gussets (for front axle mounting), 4 — middle cross members (75X75 angle), 5 — box section of the frame, 6 — bracket for additional bearing (75X75 angle), 7 — brace, 8 — beam for mounted implements, 9 — bushings with 24 mm inner diameter, 10 — rear cross member (100X80 channel).
The mini-tractor frame has a trapezoidal (front) part and a box section (for mounting the GAZ-69 transfer case and driving half-shafts). It is a welded structure. The side members, front and rear cross members, and the beam for mounted implements are made from 100X80 mm channel, while the other frame elements are made from 75X75 mm angle. Gussets made from 10 mm steel plate are welded to the front cross member. Holes 18 mm in diameter are drilled in them for an axle to securely mount the front axle.
The location of the mini-tractor’s units and parts on the frame is clear from the drawing, which shows the Muravey with the hood raised. At the front is the battery; above it, on T-shaped (front) and L-shaped brackets, the fuel tank is securely mounted. The engine itself is mounted on stands or clamps.
1 — sprocket Z=16, 2 — hitch drive lever, 3 — bushing with plain bearing, 4 — chain with 19.05 mm pitch, 5 — rod (10 mm diameter rod, 450 mm from chain to lever), 6 — main hitch drive axle, 7 — cam, 8 — rib, 9 — brace, 10 — beam for mounted implements, 11 — lever, 12 — upright (length — 500 mm), 13 — bracket for mounting the upright to the rear panel.
The body panels are made from 1.5 mm steel sheet and painted with automotive enamels.
1 — sprockets Z = 19 (from the rear hub of a racing bicycle), 2 — sprockets Z = 13 (from a children’s bicycle), 3 — plain bearings, 4 — low (high) gear lever, 5 — reverse lever, 6 — GAZ-21 gearbox.
Much attention was paid to the mini-tractor’s electrical equipment. Front and rear lighting, turn signals, and a horn are provided. The instrument panel has indicator lamps for neutral gear, high and low beam, battery charging, and brake operation.
TECHNICAL SPECIFICATION OF THE “MURAVEY”
Overall dimensions, mm … 2610X1080X1350
Wheelbase, mm … 950
Ground clearance, mm … 280
Weight (without trailer and mounted implements), kg … 400
Engine: single-cylinder, two-stroke … Tula-200
Engine power, hp … 14
Transport speed, maximum, km/h … 40
Working speed, minimum, km/h … 2.5
«M-K» 3’91, N. KOCHETOV, our special correspondent.
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