A tried and tested BM gangsaw, custom built by BM to meet Breton’s own specifications.

Thousands of BM gangsaws have been built and it is without a doubt the most widely used gangsaw in the world.

Precise sawing thanks to the rigidity and well sized steel frame with 4 columns that constantly guide the block lifter platform as it rises. Sawing is fast thanks to the 800 mm saw travel running at 90 strokes per minute and the high-mass, large diameter flywheel that adjusts the driving force.

The platform on which the block trolley rests during sawing is placed between four columns and is lifted by 4 x 90 mm diameter worm screws, with a 12 mm trapezoidal thread.
The four worm screws are fastened to the platform. The platform is lifted through the rotation of the lead screw nuts fitted on the top of the column, in a properly protected position. The nuts are turned by a system of bevel gears, drive shafts and inver ter motor 

The horizontal level of the platform is constantly checked by a device that stops the gangsaw if the platform tilts.

The blade holder is made of steel plates joined solidly together, each of which has a section of 800 x 600 mm, and slides on straight ar ticulated guides that are practi- cally maintenance free.

The 3,300 mm diameter flywheel weighs 8 tons, and guarantees a constant cutting speed, thanks to the high ratio between the inertia of the rotating masses and the inertia of the masses with an alternating movement.
The two bearings of the flywheel shaft are held by two carriers designed to make them easy to check, adjust or replace the bearings, without having to demolish the reinforced concrete foundations.
The 110 kW motor drives the unit through seven 480 mm belts with a low friction coefficient.
A hydraulic joint on the motor drive shaft, assists gangsaw start-up and reduces energy consumption.

The two cranks on the flywheel drive two connecting rods which transfer the movement to the blade holder. The connecting rods are made out of a machined steel monobloc and are suppor ted by bearings running in an oil bath.

The system with two connecting rods provides clear and time tested advantages over a single connecting rod system:

A circuit of steel gangways with railings and access steps makes it easy for operators to get around the machine. The control panel has a color touch-screen, which is used to program the machine and control the work phases.

An optional electronic program can also be supplied, which automatically adjusts the downfeed on the basis of the type of material being sawn. This system automatically regulates the downfeed speed according to the electrical power absorbed, allows the operator to set different downfeeds based on the block heights and also set the heights where the machine stops for preparing the wedges.