Friday, 08 March 2019 14:46

Post driving made easy

Written by  Mark Daniel
Mule Series V ensures post driving isn’t all brute force. Mule Series V ensures post driving isn’t all brute force.

FencePro is well known for its range of post drivers to suit all types of operation — basic farm-spec machines to high-end units for contractors who work in the toughest environments.

The latest offering from the Palmerston North company is the Mule Series V, developed from an idea to make post drivers easy to fit to a wide range of vehicles. 

Besides easy fitting, the design brief was to maximise the drop speed of the block, eliminate rope whip and use standard 0.5 inch QRC couples on the pressure-and-return lines to make plumbing simple. This latter point brought a challenge: as the hammer block descends it needs to displace a large volume of oil on the return side of the hydraulic circuit. This usually means that standard 0.5 inch couplers will not let oil pass quickly enough, so restricting the falling speed of the block.

To overcome this issue, Fencepro has designed the Versatile Hydraulic System, an ingenious hydraulic circuit that requires only a small amount of oil to pass down the return line as the block descends. This allows the block to fall at maximum velocity, so increasing driving power.

But this leads to another complication: a free-falling block suffers from rope whip, an issue that has safety implications and causes premature rope wear. Usually, a slight hydraulic restriction stops the rope from coming loose, but this tempers the driving force of the hammer.

To counter this Fencepro devised Activeblock, which effectively eliminates rope whip by taking up any rope slack after the post or a rock spike has been hit, so eliminating both issues. 

The system can be fitted to the maker’s Mule or Ultra series drivers and is recommended for Versatile series machines because the system increases the problem of rope whip. 

Note that the Mule units can be ordered with or without the Versatile system.

While plumbing post drivers to farm tractor hydraulic systems is a simple task, the same can’t be said for excavators or dozers. Tractors usually have a free flow return port, but excavators require a separate high-flow case drain set-up that can be costly. 


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