Adding Counter weights?

I have a bobcat 337 w/long arm kit, thumb and ex40 flail mower. It's manageable within reason but I'd like to add a thumb saddle and ground roller to the mower. I am concerned the added 100+# will reduce my reach enough to be a problem. Can I add to my counterweight? How much is enough? Can I just weld some plate to the existing counterweight? Or should I drill and tap the counterweight and bolt up additional weight?

ak_snowbear said:

I have a bobcat 337 w/long arm kit, thumb and ex40 flail mower. It's manageable within reason but I'd like to add a thumb saddle and ground roller to the mower. I am concerned the added 100+# will reduce my reach enough to be a problem. Can I add to my counterweight? How much is enough? Can I just weld some plate to the existing counterweight? Or should I drill and tap the counterweight and bolt up additional weight?

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If It were me, I would Not Weld anything what so ever to the counterweight. The tap and drilling, of the counterweight Is still changeing the design of the machine...and that part could get you In trouble, If something went wrong.

I would hop over to the normal size excavator forum and throw the question out there. I am pretty sure that they add heavier counter weights to machines when they are configured different as in different booms or sticks. I saw a 200 deere that had a big hammer style mover on it. It had a seperate motor, oil tank, etc mounter above the counter weight to power the mower and act as additional weight to offset the attachment. If you do add weight I would make it so you could remove it if you wanted. Mabe make a bracket so you could use tractor weights?

Let me know how it works out. I never thought about adding to the counter weight to offset some of the stuff I hang off of mine.
Good luck!

I have seen a Komatsu pc -40 for sale local that had 22' of reach , it was for sale for over a year for reasonable money . It had a 4" thick add on counter weight on the back . So it can be done.

I was just on a site that offered stick extentions and they talked about adding additional counter weight with the extention.

I was thinking one way to do it on my machine would be to make a new rear engine guard plate out of some 1' plate. It would be out of the way and nearly at the very back. I think 1'' plate is around 40 pounds a square foot so it would be easy to get some weight back there without losing any swing clearance.

I have added counterweight to all kinds of excavators. They are made with a lot of different materials and that will usually decide how you add more to what is already there. I've seen cast iron, cast steel, steel shells with concrete inside and steel shells with lead inside. You have to find out what you have before you try drilling into or welding onto the existing weight. You also need to look at how the existing counterweight is mounted and be sure those mounts will support the extra weight. Mini excavators do not usually have a robust mounting in the first place.

The other critical issue is how much weight to add. You are usually adding weight to keep the machine balanced when handling loads outside of the manufacturer's specification. What I have done in the past was use a ratio of the boom and stick length from the center of the house against the distance from the center of the house to the center of the counterweight. I use that ratio to figure how much more weight on the counterweight I need to get the machine balanced with the boom and stick out. For example if the ratio is 5 to 1 then I would have to add 500 pounds to the counterweight to pick an extra 100 pounds with the boom and stick out.

Hope this helps.

Thanx guys. The cw on this machine is mounted under the engine. I appears to be steel plate. I suppose it could be steel w/lead. Maybe I can use a hammer and judge by the sound if it is solid steel. I have seen steel/cement before. There is about 5" between the cw and the tracks so I was thinking I could easily add 2" of steel plate. Bolting would be best for sure and I'll look into that. I think the existing bolts holding the cw can hold more and will measure them first. I thot of adding to the tail/engine cover but don't like the idea of increasing the load on the hinges. I already have problems with the latch after bumping the tail into some trees.

I am not concerned with changing of the design. The machine wasn't built to haul/run a mower all the time but they didn't have any problem selling it to me that way. The only trouble I'm concerned about is added wear & tear on the slew ring & bearing.

I should probably call bobcat to see if they sell a larger cw. Not that I'd buy it from them.