Ref Report # H09A0326A
I am a moderator on Hearth.com, the worlds largest website for people that heat with wood, and as such we engage in considerable discussion of the equipment involved in processing firewood, including log splitters. My username on the forum is "Gooserider".
One of our users, known as "Woodsroad", reported a problem with his 30 ton Harbor Freight log splitter. This led to considerable discussion on the forum, detailed on pages 6-8 of the thread "My 30 ton Harbor Freight splitter experience" link -
https://www.hearth.com/econtent/index.php/forums/viewthread/23743/P75/
As I have the same model splitter from a later year, I was concerned, especially since I remembered having seen a recall on Brave brand splitters for what sounded like the same failure - see CPSC recall issue 09-174. The Brave recall mentioned injuries including a hand amputation caused by this defect.
On the website "Arboristsite.com" there was a report of a similar failure on a different and older HF splitter and discussion of the appropriate repair techniques, which essentially involved properly torquing the nut involved to 4-500 foot pounds, and applying a high strength thread locking compound (red Locktite). Link -
http://arboristsite.com/showthread.php?t=41540. While not a hydraulics technician, I would think that similar results could be attained by use of an appropriate self-locking nut, or a mechanical retention method such as a cotter pin to prevent the nut from loosening.
Note that this is a type of repair that is well beyond the abilities of most consumers as it requires special tools and knowledge. There is no way for a consumer to proactively check that this nut has been properly assembled, and in the normal course of usage, no reason for a consumer to do so. Hydraulic cylinders are normally considered sealed units that would only be dismantled in the event that they required servicing after thousands of hours of use.
Hydraulic wood splitters are also very generic in their design and construction. While there are many manufacturers of splitters, they are made by combining a very small number of parts that come from a short list of suppliers. It is very likely that if a serious problem is found with this brand of splitter, there would be many other makes that use hydraulic cylinders from the same source.
As detailed in the Hearth.com link mentioned above, I contacted Harbor Freight myself, and was told by their tech support that they have no way of determining if or when any design changes have been made that would prevent this type of failure.
While capable of causing severe injury if misused, a log splitter is relatively safe under normal conditions, as the hydraulic cylinder can only move when the control valve is actuated, and then the movement is highly predictable. However, if the nut holding the piston and cylinder rod together comes off, any actuation of the control valve will cause the cylinder to extend to it's fullest extent suddenly, with no warning, and at a much higher rate than normal. It will then be locked in this fully extended position until such time as the engine has been stopped, and the valve manipulated in the proper way to release the hydraulic pressure - this may also require partially disassembling the unit. A user that had a body part trapped in this way might well be unable to rescue himself. Since normal splitting practice frequently involves manipulating the wood to be split in the working area of the tool, there is considerable risk of entrapment or injury.
