Fixing a hedge trimmer

As the weather gets warmer, the sun graces us with its presence and we are all in lock down what better time to get out the garden tools and spend all the free time sorting out the garden.

If you're like me you will start with the hedges, then move on to the grass so the trimmings get cut up with the grass. You go to the shed, take the hedge trimmer out, plug it in, hold it in both hands and you go to do the test of all electrical tools and give it a couple of revs to inform all the family and everyone in ear shot I am going to own this job like a pro, stand up proud and pull the trigger to the realization "OH FUDGE" (or something of your own design) it doesn't bleeding work.

Calm down you can fix it just follow these steps.

Step 1-  Why doesn't it work.

When you pull the trigger can you hear a noise, if so there might be a seized part, blades or a slipped part inside.
Try a spray of lubricant on the blades and just inside the casing leave it for a few minutes and give it another go. No Luck, move to the step 2.

If there's no noise I would try checking the power lead for damage, the wiring and fuse inside the plug first. 
If the cable is broken or damaged see my post on rewiring a hedge trimmer.
OK. The fuse and wiring are OK and still not working, try it in another outlet so we can remove the simplest things before going into the hedge trimmer just to find out we didn't need to.

Step 2 - Lets get it open.

Right all previous checks look good so now move onto making sure the trimmers are not plugged in and then and only then open the case.

Firstly I need to remove the case screws and screws for the guards

• The blade guard will slide of easily
•  the handle guard was a case of going down and around the handle to remove it. 

Once the hand guard is removed you need to remove the front trigger.

• To remove the front trigger you have to lever one side out of the square slot on one side and the other will follow when pulled out.
• Remove the case screws and carefully pull of the case.

Step 3 - The Guts

This is the momentary safety switch mechanism, if you pull the trigger on the rear hand rest it pulls up the left side and if you push the secondary trigger at the front it pulls up the right side making contact with the momentary switch and turns the hedge trimmers on.
Things to look out for on this

1.  Make sure the electrical connectors on the switch are not corroded these can be replaced with some small spade connectors and a pair of crimps.
2. Check the steel wire is firmly in the plastic pivots socket.
3. The right side of the plastic pivot is inside the metal bar connected to the front trigger and straight.
4. Check the washer and spring are in the correct position and the whole thing is moving freely.

 This is the motor screw drive assembly.

1. There's a white plastic fan for cooling the motor attached to the motor shaft 
2. At the end of the motor shaft there is a small screw type gear that drives the larger gear 
3. The larger gear in turn rotates the cams.
4. The cams move the blades back and forward.

 Check all the teeth of the gears for ware and tare and make sure the assembly moves easily.


It wont rotate all the way unless you pull the momentary switch pin up as it stops the gears turning.
The holes on the blade plates that surround the cams need to be checked as they can become worn and slip off the cams and get jammed.
The picture to the left shows how it should look.
This is where my problem was, the plates had slipped jamming the mechanism causing the motor to almost burn out.




This is the picture of my problem as you can see it slipped of the cam causing it to seize.
This needed me to remove the blades, and motor assembly to realign the top blade which I will go through next.

Step 4 Removing the Blades

To remove the blades unscrew 
the whole assembly (circled screws) so you can lift it up out of the case just enough to get to the blade mounting screws (left bottom pic) undone and remove the cir-clip at the bottom of the cam drive (bottom right).

• Use a Pozi drive screwdriver to unscrew the two fixing screws.
• Use a pair of cir-clip pliers to remove the cir-clip.
• Use a hex key to remove the two bolts holding the blades to the motor assembly. 

• Now the blades are free undo the nuts up the length of the blades to allow the blades to separate so you can concentrate on the one that has seized or jammed.
• Turn the cams slowly whilst slowly prizing the blade plate over the cam taking care not to bend it.

After a while it fell in place and seemed to have no damage so I reversed the steps to reassemble the blade system and connect it all together again.
Make sure all pins and springs etc. was in the right position with no trapped wires and carried on to putting it all back.

After everything is back where it needs to be make sure to give all mechanical moving parts a good covering in grease to prevent seizing.

I had an issue with the spring of the front trigger but it was a simple fix just had to shake it free from the case and push it back into the recess and hooking it over a screw hole on the case opposite.

After all this its time to try it once the case is all put back together and everything is checked, greased up and your happy of course.

You should find that your Hedge trimmer is in good running order so........

GO CUT THOSE HEDGES LIKE A PRO!