CAD Drawings of the MÁV Class 342 steamer model

MAV Class 342 loco general CAD drawing minipic

CAD drawing of the loco. This contains all details that should be present on the model. For the better appearance also coal will be added. On the model a pile of coal is essential, as it should hide the flywheel.

Class 342 steamer model arrangement CAD Drawing minipic

CAD drawing of the drive arrangement. Only the 3rd driver will be driven by a gearset, the others by the siderods. The 1st and 2nd drivers will be compensated.

MAV Class 342 Model New Gaerbox Version mode minipic

CAD drawind of the general arrangement with the new type gearbox. As the idle gearset has moved forwards there is a possibility to put it into the firebox. The flywheel has also moved in front of the gearbox. It has a recessed front in order to accommodate the motor shaft and the joint. This way the motor was moved forwards only a small extent. The frame, its spacers and fixations remained as they were before, just the center spacer needs a little filing at its back edge to clear the idling gearset in its new position.

The frame CAD drawing. The frame will be made of two parts, as the leading axle needs much more sideway movement possibility than on the prototype. While the same problem will be solved at the trailing wheels by a non-prototypical cutout of the frame, this is not possible for the leading wheels, being on a much more visible area. Instead a narrower front frame will be soldered to the mainframe.

The top view of the frame. The narrower front part is well visible. This is necessary because of the sideways movement of the leading axle. As on the prototype both the leading and trailing axles were suspended in the frame as Adams-axles, the frame has no cutout for the wheels. The model, however, should negotiate sharper curves, as low as 22" radius. Therefore the frame is narrower on the front, the trailing wheels have a cutout in the frame, unlike on the prototype.

Class 342 steamer model drive CAD Drawing minipic

The drivetrain CAD drawing. The can motor drives a bevel gear with 35 teeth through the worm. The 25 teeth axle gears are driven by a 30 teeth gear being on the same shaft as the bevel gear. All gears are of metric module 0.4mm. The flywheel is behind the gears, in the coalbox.

MAV Class 342 steamer model new gearbox minipic

The new drivetrain CAD drawing. A small design flaw in the previous design allowed to decrease the size of the gearbox using the same gears, that fits now inside the firebox. This way the flywheel can also be placed inside the boiler rather than in the coalbox. In order to restric the length the flywheel needs to be recessed.

Class 342 model equalization beam CAD minipic

The equalization beam of the model. Only the first and second drivers are equalized, the third one is mounted fixed in the frame. On the prototype the second and the third drivers were equalized, the first one was only sprung suspended.

Class 342 model leading and trailing axle suspension CAD drawing minipic

The suspension pivoted trucks for the leading and trailing axles. This is unprototypical as the real engine had Adams-axles. The front truck is lowered, as it should move sideways below the lower edge of the frame front.

MAV Class 342 steamer model cylinder block design minipic

The cylinder "casting", both the front and back sides. They are indeed soldered from 0.5mm brass sheets, the cylinder rings are glued on the surface.

Class 342 model crosshead assembly CAD drawing minipic

The crosshead and the crosshead guide. As the crosshead guide is rear open, it is possible to place the crosshead later. In the case of the Class 326 model, the crosshead should have been assembled first.

Class 342 minipic valvegear CAD drwaing minipic

The valvegear. The Class 342 prototype had a full Walshaert valvegear with a construction usual in in Europe in the 1910's. In the model all moving parts will be made from nickel silver.

Class 342 model yoke CAD drawing minipic

The yoke. It will be soldered to the cylinder block assembly that makes easier to remove it. The crosshead guide back end will be soldered to the yoke too. The circle in the center is not part of the yoke, it is a design aid showing the exact position of the piston rod. This is the basis for the yoke design. The dual hole on the upper part of the design is the mounting hole for the reverse link holder. The small hole with the I-beam shape is the connection for the I-beam, that - as on the prototype connects the yoke to the cylinder block casting.

MAV Class 342 steamer model cylinder rings design minipic

The cylinder rings. The pattern of small, 0.4mm (0.00157") diameter holes were made using the CNC-drill. The next step was to cut off the disks in the lathe. Brass wire of the same diameter is glued in each hole and grinded flat to model the ring fixation bolts.

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