Thread: Parkanson Power Hacksaw

i was going to ask you about a top seal. Nothing on mine as you say but the top of the cylinder looks to be machined to fit something. There was a heap of dirt in it. There are several holes and grub screws in the cylinder that I need to understand. Once fully cleaned I will try to map out the system to understand what it is doing.

Top of the main ram just has a metal cap with a slot in it for the connecting rod to go through.
Not a seal as such, just enough to stop fat kids and their donuts falling in...

Steve

Hers a piccy



Steve

A few pics of the strip down and repainting. The black paint is POR-15 which is as tough as nails once set. I used this on all surfaces that would be in contact with the coolant including the inside of the coolant tank.

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I have completed most of the repainting in Epoxy Enamal and will get pics soon. Now I need to decide whether to make new shafts as the 2 critical ones are quite worn. I also need to strip and clean the coolant pump which is seized.

Steve, my hydraulic block/system seems different to yours. I have mapped out the system and will post a pic of what I 'think' is happening so that I can be certain. More PC time needed

OK I have mapped out the hydraulics on this power hacksaw and believe it works as follows. Please correct me if I am off base.....

My hydraulic unit has a selector lever on it that has 2 positions (right hand side of pictures), either up or down, meaning that there are manual inputs/options available. When this lever is UP, the hydraulics allow the blade to lower gradually but provides lift on the non-cutting stroke. The amount of downfeed is governed by adjusting the needle valve (left of pictures). With the lever up there are 2 scenarios being the hydraulic pump is pumping or is not pumping.

Selector Lever UP, pump pumping;
Hydraulics1.jpg

As the pump moves down, it pushes fluid into the main cylinder from which it is prevented from escaping so the main cylinder raises slightly (blade backstroke).

Selector Lever UP, pump not pumping/retracting;
Hydraulics1a.jpg

As the pump retracts, the weight of the blade assembly pushes down on the main cylinder forcing fluid out, via the needle valve, through the selector lever and out into the fluid reservoir.


Selector Lever DOWN, pump pumping;
Hydraulics4.jpg

As the pump moves in, it forces fluid into the main cylinder from which it cannot escape. The main cylinder/blade therefore rises.

Selector Lever DOWN, pump retracting;
Hydraulics3.jpg
As the pump retracts, fluid is 'sucked' from the main cylinder causing the cylinder/blade to fall. The net effect of the selector lever being in the down position is that the hydraulics effectively do nothing.



I have another theory about the selector lever being down and that is that in that position it is intended to allow the blade to automatically lift. The holes at the very top of the main cylinder are there to bleed off fluid if the blade gets to the top of its travel. I cannot actually see how this would work with the provided plumbing but is the only explanation I have for the holes at the top of the cylinder.

Am I on the money? Off base? Stating the obvious???

Just looked back over your other photos - is it possible the selector valve on yours could be pushed down by the main arm casting when it drops to a certain point?
That would make more sense than it being just a manual valve there with seemingly no purpose.

Definitely a different hydraulic arrangement to what is on mine.

On a different note, I don't recall if I mentioned it previously but the dovetail on mine is quite worn in the middle so has quite a bit of play but I can't adjust the gibs to remove it or it binds at the ends of its travel.
That results in a bit of vibration of the blade when its cutting.

Really needs a rough scrape/machining to fix it so the play can be adjusted out. Another job for the TODO list...

FWIW - I gave my cylinder a quick go with a brake cylinder hone to clean it up. Not perfect, but I figure as long as it seals well enough for the ram to raise on the back stroke then it will be fine.

Steve

The selector lever has the usual plastic ball on the end so intended for hand operation. I cannot see any way the main arm could interact with it.

My Parkanson saw is pretty much finished.

To address a point from below about the selector rod, now that it is together I can see that I lift up the selector to start it feeding down and then when the saw is all teh way through the material, the top arm (holding the saw) pushes the selector back down to stop the down feeding process.

I have rewired the saw with new orange circ as the old wire was a little crusty. I repaced wire for wire so that I knew it was correct (I am not an electrician) BUT once finished I noticed this little red wire hanging around. It must has slipped out of somewhere without me knowing. Does anybody know where it needs to go back into??? My best guess is that it goes on the blue output wire (input at the top and output to motor at the bottom);

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Hi I have a cast iron a Parkanson PHS. My biggest problem was getting it out of my van previous owner had a truck with a hoist so it went in easy enough. A mate loaned me an engine hoist so problem solved, first time I have used one. The cap for the hydraulics cylinder is missing on mine, I think I will use a bit of poly pipe with cap, once it is painted it will blend in and be just as good keeping crap out. My coolant pump was missing so I have put in a submersible fountain pump, works fine so far and it is adjustable. My coolant tank is two chambers a collection side and a supply side there is a hole between which had a filter that had decayed, replaced it with a stainless steel tea strainer stuck on with metal bog. I also stuck a magnet in the collection side and clean it off occasionally.
Have had problems with packers I am going to get some rectangular tube and bolt it to the back jaw for 45 degree cuts and better use of blade. I broke a blade cutting a bolt that was less than half the jaw width. Found out there is a hole in left side of rear jaw where your can put a bolt to stop it pivoting on short pieces of stock.
I replaced the original 3 phase motor with a single phase made sure it was the same speed and it came with a pulley the same size. Had to drop the fan to fit it in but I make sure to keep jobs short so it won’t overheat. I intend to repaint the saw, I have painted the coolant tray with engine enamel and started with some rattle can spray but I think I will redo both with POV 15.
good luck with the rebuild, the saw is so much better than an angle grinder.

Very nice Tootsie. Probably older than mine as your is cast iron but pretty much the same layout. I am very happy with mine and I am sure you will be with yours!

Hey, nice work. I have just picked up one of these great saws, everything works except the hydraulics. I've been looking for info before I started to dismantle.

So I filled with fresh oil and cycled, lifted, lowered all while running etc. No pressure. Any advice on parts, seals etc to make the overhaul less complicated?

Thanks,

Originally Posted by Mk1_Oz

OK I have mapped out the hydraulics on this power hacksaw and believe it works as follows. Please correct me if I am off base.....

My hydraulic unit has a selector lever on it that has 2 positions (right hand side of pictures), either up or down, meaning that there are manual inputs/options available. When this lever is UP, the hydraulics allow the blade to lower gradually but provides lift on the non-cutting stroke. The amount of downfeed is governed by adjusting the needle valve (left of pictures). With the lever up there are 2 scenarios being the hydraulic pump is pumping or is not pumping.

Selector Lever UP, pump pumping;
Hydraulics1.jpg

As the pump moves down, it pushes fluid into the main cylinder from which it is prevented from escaping so the main cylinder raises slightly (blade backstroke).

Selector Lever UP, pump not pumping/retracting;
Hydraulics1a.jpg

As the pump retracts, the weight of the blade assembly pushes down on the main cylinder forcing fluid out, via the needle valve, through the selector lever and out into the fluid reservoir.


Selector Lever DOWN, pump pumping;
Hydraulics4.jpg

As the pump moves in, it forces fluid into the main cylinder from which it cannot escape. The main cylinder/blade therefore rises.

Selector Lever DOWN, pump retracting;
Hydraulics3.jpg
As the pump retracts, fluid is 'sucked' from the main cylinder causing the cylinder/blade to fall. The net effect of the selector lever being in the down position is that the hydraulics effectively do nothing.



I have another theory about the selector lever being down and that is that in that position it is intended to allow the blade to automatically lift. The holes at the very top of the main cylinder are there to bleed off fluid if the blade gets to the top of its travel. I cannot actually see how this would work with the provided plumbing but is the only explanation I have for the holes at the top of the cylinder.

Am I on the money? Off base? Stating the obvious???

I haven’t had a problem with the hydraulics on my PHS. I replaced the oil with hydraulic jack oil and performance stayed the same. There is no gasket on the sump only an o ring on the control rod, maybe have a look at that. Wear on the pump perhaps? All the best with your power hack saw.

dan, I would agree with Tootsie. The only seal on mine is the one he talks about - on the plunger that is attached to the rotating shaft. The top arm is connected into the vertical hydraulic cylinder/tube. The plunger in there does not have a rubber seal but relies on a tight fit. Maybe yours has wear in there. Also, check that the hydraulic assistance/pressure valve is opened - mine has one but I do not think all models had this - I can turn the hydraulic raise/lower on and off and also adjust the speed of the cut.

I've just picked up on this thread. My Parkanson power hacksaw 6 x 6 is very similar to yours MK1_Oz . The piston on mine has two cast iron piston rings on it which are a bit worn. It still works well though I need work out what is going on with the 45 degree cuts as they aren't quite right (to set mine to 45 degree you loosen and swivel the back vice and two pins go into holes one for the back vice (fixed jaw) and other for the front. One day I will do a restoration on mine. I've always kept a watch out for a manual for it, but never found one.

Originally Posted by steran50

...The piston on mine has two cast iron piston rings on it which are a bit worn...

Interesting that there is nothing on mine. I have thought a few times that my piston looks to be a remade part so maybe it is and they just simplified by removing the rings.