Battery powered wedge

[d0m3n]

Hello, I'm a mechanical engineering student and I have to design a battery powered felling wedge, I know hydraulic and mechanical ones are already available but my assigment is to design one using a built in electric motor. The design process includes market research and identifying customer needs, so since I never cut a tree down myself I wanted to ask here for some insight.

The only requirement I was given is that the wedge will be used on trees with diameters ranging from 8 to 40 inches. From what I saw online these are only used when you want the tree to fall where it wouldn't normally, on difficult terrain where winching isn't possible. If the wedge was practical enough, would it be used more often or is it easier to just use normal ones and an axe?

Who would use this tool? I'm guessing people who cut down a lot of trees, what are their needs? I'd say the main requirements would be low weight, robust build capable of operating in all weather conditions, long battery life (how many trees should it last?) and easy to change battery. Does anything else come to mind, like the ability to operate the wedge from a safe distance or any other wishes? What would make you want to buy one and also why wouldn't you want to use it?

Here is an example of a hydraulic wedge: Hydraulischer Fällkeil von Nordforest - www.grube.de - YouTube

If someone here already uses the mechanical or hydraulic one, when and how often do you use it and what would you change or improve on it?

Thank you very much for your insight.

[Skeans1]

That looks heavy and honestly dangerous it’s likely to kick back out of a cut at you. I use jacks for doing the same purpose they’re mostly back pack setups to make packing in easier.

[Southside]

Good luck with your project.  One thing folks who fell timber don't like much is complication with equipment.  Battery says to me switches, chips, wires, and things that don't like to get wet, walloped around, or otherwise abused.  Can you build one - I am sure.  The real trick would be in making it so simple and reliable that guys are willing to buy it.  Charging and or replacing batteries is not something that will be appealing.  

If a tree falls onto a simple felling wedge odds are other than getting dirty nothing is going to happen to it, you will have to compete with that standard.    

[mike_belben]

Small electric motor with a winch planetary that turns a worm gear leadscrew which spreads the duckbill.  The motor should have a thrushaft so that a hex end sticks out the back and matches the size of a chainsaw sparkplug so the feller can still crank it with his scrench if the battery dies.  

Otherwise i guess id have to suggest a self contained electric over hydraulic to push a ram like you linked, but that might get heavy and infringe on patents. 


Its gonna be hard to compete with the time tested bottle jack.. Just fyi.

[Riwaka]

There is already the Forstreich felling wedge that is used with a lithium battery drill. Looks to work okay where the tree cutters work as a cutter/ spotter pair. As lithium drills get even more power(as lithium batteries or other electrical power storages develop) , the mechanical wedges are likely to suit dry steep places. (where there is little chance of dropping the drill in a small pond of water at a tree base etc)

There are some good videos of the pro German and Austrian tree fallers with stihl/ husqvarna chainsaw  using Forstreich wedges with  milwaukee drills on the right sized trees ( relatively small trees 15-24 inches at the stump diameters) and tipping the trees in the direction they want, might be quicker than a plastic wedge with a axe or mallet.

The following video is not a good example.
This tree faller (with a Milwaukee drill and mechanical felling wedge) looks a bit rough, you can tell by the state of his plastic wedges.


These guys looked better, their plastic wedges are in better condition. From 14.00 (2 minutes at end)The tree is a bit smaller? too.
Holzfällen mit Fällkeil ValFix und TR 24 AQ Uncut - YouTube

[Southside]

Better keep a good supply of the right sized socket for that set up!!  

[upnut]

A better market other than full scale logging might be arborists and tree removal companies that deal with extricating trees in tight quarters. HolmenTree on this site might chime in...

Scott B.

[mike_belben]

I agree.  An arborist is hired to do the hardest tree.  Your average logger passes over it.

[Skeans1]

I agree.  An arborist is hired to do the hardest tree.  Your average logger passes over it.

What are you going to trust when you have to push something big and heavy over an impact setup or hydraulic rams? These are falling jacks the lift capacity is 125 tons combined.

You’ve got a gauge, check valves internally, plus a floating plate for doing the worst of the worst, and you can do up to 4 rams per pump for 250 tons of lift.

[mike_belben]

 youre not the avg logger skeans.

I just looked at an almost done 500 acre clearcut other day on my late buddies place.  Logger doesnt even own a winch.  2 big cat grapples.

[Skeans1]

youre not the avg logger skeans.

I just looked at an almost done 500 acre clearcut other day on my late buddies place.  Logger doesnt even own a winch.  2 big cat grapples.

Out here that’s a very common setup that’s been around for 60 years.
Some of those big skidders do have winches some don’t if you’re not needing a line much why have the extra weight and maintenance of a winch.

[mike_belben]

Appalachian hardwood harvests are mostly a free for all highgrade scramble so the best wood is just over the bluff where the last 2 hacks passed it up.

[Jeff]

Critical mass! Teetering, teetering, just a little more...
DANG! Run! Battery died!

[Crusarius]

Look into battery powered extrication tools. My fire department purchased a set and they are now the go to tools for extrication. I am not going to say they are light, because they are not. But they do not have hydraulic hoses or require a hydraulic pump. I am pretty sure they are electric over hydraulic. So an electric motor spins a hydraulic pump that powers a ram. The hydraulic pump is two stage so after the high speed can't move it anymore the low speed kicks in and gives it around 12000 psi of compression strength.

That ram setup that skeans shows is pretty sweet, but not something I would want to drag around. The extrication tools are hard enough but could be simplified treemendously (intentional pun) to work very well for what you are tasked with.

[Skeans1]

Look into battery powered extrication tools. My fire department purchased a set and they are now the go to tools for extrication. I am not going to say they are light, because they are not. But they do not have hydraulic hoses or require a hydraulic pump. I am pretty sure they are electric over hydraulic. So an electric motor spins a hydraulic pump that powers a ram. The hydraulic pump is two stage so after the high speed can't move it anymore the low speed kicks in and gives it around 12000 psi of compression strength.

That ram setup that skeans shows is pretty sweet, but not something I would want to drag around. The extrication tools are hard enough but could be simplified treemendously (intentional pun) to work very well for what you are tasked with.

That setup is a full back pack setup weight of the old ones like that was 60 lbs or so considering what they do they aren’t horrible but normally you’re packing into a nasty hole with a long bar and a spare saw for limbing.

[Ed_K]

 What happened to the like button? Jeff's was right on.

[Haleiwa]

Sometimes an assignment like that is as much for the instructor to see which students understand practical considerations as much as a test of design skills.  I knew of an ag engineering class that was instructed to design a portable calf hutch; one submission included wheels and an engine to drive it around.
As for your assignment, start by considering what it will replace.  Two or three wedges and a logger's axe are about as idiot proof as you get, fairly light, and easy to carry around.  To be marketable, your wedge needs to be simple, easy to carry around, and reliable.  To start, I would set some parameter goals.  Ten pounds or less, as much metal and as little plastic as possible, and using an existing battery system (Milwaukee Fuel is a good one).  I think I would use a jack screw to spread the wedges, and have a metal "heel" that allowed the wedge to be driven into place with an axe, just like the non powered version.  Forget about remote controls, flashing lights, sensors, and the like.  A logger who can hit a wedge with an axe has a pretty good sense of when to increase the pressure on the wedge.  Push the trigger and it expands.  Push the reset button and it returns to its relaxed state.  A couple of barbs to prevent it from slipping out of the kerf, maybe a replaceable aluminum tip in case the saw hits it, orange paint to make it easier to find if it goes flying, and a belt pouch to carry it around.  If you want to be price competitive with the wedge and axe system, you probably need to set a top end of under $500 or so.  In hand logging, simple and reliable beats sophisticated every time.