KAT excavator - upgrade

[Rimrock]

Hi all,

As I did notice the threads about the relative new excavator on the market, the KAT out of China, I got curious about the thing and order one myself. Well, it just dropped down on my bench this weekend I did pick the basic version without any hydraulics, but it was delivered with the track and swivel motors.

Scale;
I like numbers, so I had to check out what kind of scale this machine would fit. The fabricator states 1:12...nooo, can't agree on that one..The inspiration for the KAT is quite likely the CAT 365, 65-70 tons, and it seems to turn out at a scale of 1:15.5 . In the Tamiya scale, 1:13.5, it will have the size as a 25-30 ton machine, though with a bit narrow cabin version.. The width of the undercarriage is 225 mm, on the tracks, that makes it fit fine on a 1:Tamiya trailer. Generally it's a neat sized machine, fits fine operating with the Tamiya trucks (and Wedico naturally)

Compared to the 4200xl, the KAT is a bit smaller machine. Construction vise the 4200xl is a more robust, and heavier piece of equipment, as it is fabricated mainly out of 6 mm alu.plates. The KAT is mainly of 2-3 mm alu. That works out quite fine in many locations, but I see that the plate thickness should be larger on some critical points. I guess it is a combination of lack of knowledge, and an urge to make a low cost product, that is behind. The fabricator could 'easily' with some minor, and relatively cheap, adjustments risen the quality some steps. I might send him some epictures and ideas after I've completed my modifications..

Alright, my idea is to equip the machine with a Premacon pump, Magom cylinders, and not decided what valves, Premacon or the cheaper option Magom. I will just keep the cost a bit down, may sell it later on, but want a good performance. (I also am scratch building a excavator, that will be my 'number 1 operator' will post a seperate thread later on)

Initially I did not plan to modify 'the shell' of the machine, except tighten up joints and swivel, but it seems that some more work have to be done...

* Boom and dipper arm
I like the way the boom and dipper have been put together; the side plates attahed to each other in 4-6 point with countersunk screws, added threadlock, good. It seems surprisingly stiff.

- Counter sunk screws. I have made the counter sunk deeper, to be able to hide the bolt heads and make the surface flush.

- I've added a piece of 2 mm alu on each side of the boom/upper structure interface, to make it a bit more stiff.

- The original cylinders are of equal length (?) I don't have them myself. It seams that the stroke of the cylinders are adapted to the movement of the 2 boom cylinders. On the dipper and bucket these cylinders seems to have an too long stroke. Anyway, I could not get the Magom cylinders to match the max lenght needed on dipper and bucket, so I will put new cylinder brackets here, to be able to use shorte cylinders (movement will still be the same)

- Stick. As I am going to fabricate a new bracket for cylinder anyway, I just as well removed the existing one and did some other modification too. See picture. I did mot like the original open space on in each end of stick. so i made a new 'banding' plate to make the stick look a bit more real.

- I too place bushings of brass in all joints, and get rid of the 5 mm bolts, whose threads soon would had eaten up the alu.material in the holes...I will use 6 mm bolts, 'smooth surface', in the main joints.

* Engine house

-The bottom plate of the engine house is too thin, 2.7 mm. Was a bit dented and bent when delivered. Will try to 'make it flat', and possible add a flat bar running in the centre of the bottom plate, for stiffening.

- May will ad a counter weight, steel plate, in the rear end of the house, if needed.

* Undercarriage

- Plates on which track gear motors are attached, are of too thin material, 2-3 mm alu. Not stiff enough to keep the idler wheel lined up straight. I've added a bracket at the rear end of the motor, that helps things straighten up, and gives the setup much more stiffness.

- Track rollers...mmmm..come ooooon..) alright, they may work for a while. Maybe to fabricate some 'real' rollers, and get rid of the thread bolt shafts..

Puuuh, it's getting late...can we do one more....?

- The idler wheels are not attached 'straight' on gearbox shaft. Shaft diameter is 7.95 mm, and the centre hole drilled in the idler wheel is 8.3..Need make that fitting tighter

best regards
Oyvind

[Rimrock]

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[JAMMER]

This was a very nice review of this excavator. It is cheap and it shows it but it seems with a few modifications it may not be bad. Ed

[kenobi]

Hi Rimrock , what did you pay for the empty excavator shell including postage to Norway.

[rmunson21]

Awesome review. can't wait to see more of your upgrades

[Rimrock]

Originally Posted by kenobi

Hi Rimrock , what did you pay for the empty excavator shell including postage to Norway.

Did cost $995 (785 + 210 EMS shipping), + 25% VAT
Can choose to have it delivered with or without the cylinders (+ $100 for cylinders) Another owner have bought the 4200xl cylinders and hydraulics for the KAT and was more happy with them than the original hydraulics. Oztruck here on the forum can maybe comment on the quality of the original cylinders.

[liftmys10]

Good review! Thnx

[Whiskey]

Looks awesome!! Wish I had the tools and know how to do that.

If you wouldn't mind, could you post or pm me the website you ordered that machine from. Would love to check it out myself. Thanks!

[Rimrock]

Originally Posted by Whiskey

Looks awesome!! Wish I had the tools and know how to do that.

If you wouldn't mind, could you post or pm me the website you ordered that machine from. Would love to check it out myself. Thanks!

Hi, thanks) you will find the machine at www.buychina.com Search for 'excavator', show 'highest price', and it should turn up. There are 4 different variants; basic machine with or without cylinders ($8-900), complete machine with standard hydraulic and radio ($16-1700), and a machine with upgraded pump and some few minor things ($2500)
I would not consider the highest priced one at all, I feel it is not worth it, then it is better to go for the XL4200.

I have continued my KAT upgrade project and have concentrated at under carrige the last week.

- Have finished installing the extra support for track gear motors and have made the gear shaft / drive wheel connection a tighter fit. the drive gears now runs 'straight'...The fabricator could done it right at first, and saved me many hours of work.. Generally the undercarrige is of fine design. The tracks looks good, tracks are long, the drive and idler wheels are of solid steel; great.

- Started rebuilding the swivel. There is no 'slip ring' unit for the track motor's wires...mmm..It may work if to remember not to turn more than 2-3 turns in same direction, before heading the opposite direction.. Well, I have an slip ring laying around here, so I will install it. In the same 'operation' I will make the swivel / engine house connection firm, and also rise the 'swivel pipe' about 1 cm. I to feel the bottom plate of engine house to have a too small clearance to the tracks.
Actually I have moved the swivel bearing to just beneath the bottom plate, and added a 2 mm spacer ring in the connection. The original dia.90 mm plastic ring I have replaced by a longer ring, made of a modified 110 mm plastic pipe. The 'backbone' of the swivel unit is 6 off brass studs, threaded M5 in each end. What is missing is a new centre bracket for the gear, and slip ring. To be turned from a dia.40mm alu. bar.

I see now that there has been some transportation damage, as other has seen at their KAT's too. The base/bottom plate was bent, and also the cab has got a 'kick' sideways..I have an idea that the damage might can have happened in the fabrication shop..If so; not good..I would think there would been considerable damage to the cardboard box it it happened under transport from china too me..the box looks fine, just some smaller scratches.

[docfcybo]

Hi Rimrock!

How is it going with your Kat? Have you installed some hydraulics?
Bye, Fabio

[Rimrock]

Originally Posted by docfcybo

Hi Rimrock!

How is it going with your Kat? Have you installed some hydraulics?
Bye, Fabio

Hi,
I have had a pause regarding the KAT, and have spend some time building on my other excavator project, the Akerman H14b. Will get started on the Kat again a bit later)

[docfcybo]

Oh... OK.
You know, I think I'm buying (in some month) the Kat, ready to do any kind of cheap do-at-home enhancements but would love to keep its original hyd system for now. So I'm trying to understand how do it works.
Howevere, good job on your Akerman!