16mm wagons are prone to rolling away when left on a gradient. My sidings aren't all as level as they might be, so my latest wagon (a Brandbright 4 plank open wagon, kit GS6) has been fitted with a parking brake. Here's how:
First, assemble the wagon chassis, fitting the axleboxes and wheels. The two triangular hangers for the brake mechanism are made from 1/2" wide by 1/32" brass strip. The hangers are secured to the chassis by wood screws. A 2.5mm hole is drilled through each hanger for the brake drive rod.
The brake handle is made from 3/32" square brass tube, 80mm long. This is opened out at one end and soldered around the drive rod.
To operate the brake blocks, a 20mm length of 5mm wide brass U channel with a 2.5mm hole drilled through the centre is soldered to the brake drive rod in line with the wheel treads. A 1.6mm hole is drilled through either end of the channel for the push rods which will operate the brake blocks.
To keep the drive rod in place, washer is soldered on either side of the hanger on the far side from the brake handle.
The brake blocks are made from 1/16" square brass tube. A length of tube is bent around a diameter of approximately 26mm (I used a chuck collett) and a 16mm length is cut for each brake shoe. A 9mm length is then cut and soldered to the back of the 16mm length. 1.6mm holes are drilled at either end of this piece for the pivot and the push rod.
The brake block is hung from a length of 1/16" brass wire. The wire is secured to the chassis by being soldered to a piece of scrap brass sheet or strip which is superglued to the chassis. The wire is bent so that it passes through the pivot hole in the brake block, approximately 12mm below the wagon floor. The brake block should be positioned so that it rests against the tread of the wheel and pivots back completely clear of the wheel tread.
The push rods are made from 1/16" brass wire. With the brake handle in the raised position and the brake block firmly on the wheel tread, the distance between the hole in the U channel and the brake block is measured. A piece of wire is then bent to fit, so that the brake block is held firmly on the wheel, but moves clear of the wheel when the brake handle is lowered.
The second brake block is fitted in the same way as the first.
The final stage is to build the handle restraint. This is made from 1/16" square tube, bent to form three sides of a rectangle. A small length of tube is soldered to one side to form the handle rest - when the brake is applied the handle sits on top of this.
The assembly is soldered to a piece of 1/32" scrap and the whole restraint can then be glued to the underside of the wagon. It must be positioned so that the brake handle will sit on the rest when the brake is applied and can hang freely or rest on the bottom when the brake is released.
The final stage is to complete the wagon and visit the paint shop.
The complete wagon is now ready to roll, or not roll away, as required.