Both are tracked machines running on rubber tracks, with the smaller machine weighing in at 2.5t while the larger weighs in at 8t. The brothers have also introduced a tractor loader/industrial loader-mounted post driver, which was featured in our recent Ploughing roundup.

Compared to tractor mounted machines, the new tracked machines are at the other end of the spectrum. These are dedicated self-propelled post drivers, built for fencing contractors and the likes. Both are designed to be operated by one man and driven from the ground with another set of driver controls close to the post driver controls. According to Michael Brennan, the fact that these machines can be operated by one man means they provide considerable labour cost savings, particularly for professional fencing companies.

The smaller unit is a 2.5t machine and it comes with a variable weight hammer. Opening a door in the hammer reveals a chamber where weights can be added or removed, adjusting the hammer weight from 50kg to 250kg. The concept behind this design is to allow a weight reduction of the self-propelled post driver to below 2.5t − making it possible to tow on a trailer behind a 4x4 vehicle.

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Michael explained: “We had a request from Britain for a machine that could be towed on a trailer behind a Land Rover or a similar vehicle. One way to achieve this was by removing the hammer altogether. But that is potentially dangerous because of the weight of it and there is a lot of work involved in removing it. That’s why we designed it so the weights in the hammer could be removed altogether.”

The Brennan’s have designed this machine with a fixed type mast to keep the weight down. Most of the firm’s other post drivers use a telescopic mast to achieve the required amount of hammer travel. To get around this, they developed a compound pulley system for raising and dropping the hammer.

This allows them to use the full length of the boom and gives a ratio of hammer hydraulic ram to hammer movement of 3:1. That is 250mm (1ft) of movement on the hydraulic ram, which moves the hammer 720mm (3ft). For road transport, the mast can be hydraulically positioned forwards to reduce the overall machine height to 2.3m. To square the boom in order to position a stake or post, there is 600mm of side-shift available, 20 degrees of front and rear tilt (40 in total) and a side tilt of 25 degrees out and 25 degrees back again, giving a range of 50 degrees in total.

The machines drive controls are beside the post controls. A rocker switch moves the machine forwards or backwards on its tracks while an additional lever steers the tracks if needed. To remove the risk of accidental operation in either direction, the f/r reverse rocker switch will not operate the machine unless a safety button is pressed at the same time.

The 2.5 tonne tracked machine is based on a second-hand, 30hp Yanmar C30R. This machine comes with reversible seat and dual controls from manufacture. The Brennan’s then built their post driver around it, adapting the ground based drive controls to suit.

Michael added: “This unit is just 30hp so it is more fuel efficient than a conventional set-up, with a 100hp tractor and post driver.” The rear platform provides ample carrying capacity for fence posts and there is another one at the front to carry more fencing posts and equipment.

The price of the 2.5t machine ranges from around €19,000 + vat to €22,000 + vat, depending on the price of the donor vehicle.

Big tracked option

The larger 8t self-propelled post driver which the Brennan’s have developed is based on a Mitsubishi CD400 and is powered by a six-cylinder 115hp Mitsubishi engine.

Michael said: “This tracked machine has a very large under carriage and is suitable for use on very steep or soft ground. It is very suitable for work on rough terrain in general, such as forestry or hill farming.”

This is also a one-man fencing machine and Michael said that it can carry up to 200 fence posts on its rear platform with another 20 x 250mm straining posts on its front folding cradle. The overall payload is 4t. According to Michael, to help line up with fence posts, this goliath has 1m of rear shift, 900mm of side shift and a huge amount of tilt in all directions. It is fitted with a 90mm rock spike, is plumbed for a post rotator and can be fitted with a pick-up hitch.

The mast is telescopic and the height under the hammer is a maximum of 3.6m. The hammer itself weighs in at 400kg, which should be enough for the toughest of driving.

At the rear of the Mitsubishi CD400, mounted on the Vector Powerdrive post driver, is an electronic joystick to give forwards, rearwards and steering movement of the tracks.

The list price of this machine, the largest manufactured by the firm, is between €30,000 + vat and €40,000 + vat.