Type – Single
This attachment is used on L.H.T. Tractor Type III.
Its purpose is to mill or tear the bog surface to a depth of approximately ½” (12.7 mm.), leaving behind it a layer of powdered peat to be dried by the wind and sun.
The attachment is located at the rear of the tractor unit. It consists of a simple but strong tubular steel frame, the main members of which extend to, and are pivoted, at the mid position of the tractor tracks. Rigidly mounted on the underside of the frame is a pin type milling drum which is driven from the tractor P.T.O. shaft through bevel gearbox and chain drive. The attachment is supported by a ground roller, through springs, located immediately in front of the milling drum and by a depth control castor a few feet behind the milling drum. For idle travel, the attachment is lifted by hydraulic ram so that the pin milling drum is clear of the bog surface.
This attachment, by virtue of the sprung main supporting roller causes the milling drum to cut deeper on the hills and shallower in the hollows, thus having a levelling effect on the bog surface.
The drive to the milling drum is protected by a tension bolt safety device.
Type – Triple
This attachment does the same operation as the single unit but has about 2½ times the output.
The attachment consists of units similar to the single attachment, ganged together. The front centre unit is attached to the tractor draw-bar while the two side rear units are drawn by brackets from the side of the front centre unit frame. These brackets are pivoted, and the level of the front of the side unit frame is controlled by roller castors running on the bog surface.
The drives to the three milling drums are by universal jointed propeller shafts with splined slip sleeves, two bevel gearboxes and final chain drives. The milling drum speed is lower than the single unit but in all other respects the behaviour of the individual units is the same as the single miller attachment.
For idle travel the units are lifted on hydraulic rams incorporated in the rear castor roller assemblies and depth of cut is also adjusted by these rams, from the driving seat.
The drive to each of the three units is protected by a tension bolt safety device.
Off Set Miller Attachment
Type – I
This attachment is used to form a bevel on the edges of milled peat fields, to assist surface drainage.
The attachment is a miller drum, projecting from the rear of the tractor unit on a casing arm which is pivoted at a central position on the rear of the tractor main frame, and is extended to carry a ballast weight. The drive is taken from the tractor P.T.O. Shaft, through a bevel gearbox which forms the pivot assembly of the arm and a universally jointed propeller shaft extends to the actual milling drum.
The milling drum is set backwards as it extends from the tractor so that the spoil is thrown back towards the centre of the milled peat field, where it can be harvested.
A supporting trolley fixed to a projecting bracket at the centre of the tractor track and supported on a roller behind the drum, carries the drum arm on an adjustable suspension. The trolley, complete with extension arm and drum can be lifted by a winch rope passing over a mast frame mounted on the tractor.
For bogs in early development a bladed drum is used, while a pin drum is used on production bogs.