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Old 10-02-2013, 06:09 PM
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YellowDogSVC YellowDogSVC is offline
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Join Date: Oct 2006
Location: TX
Posts: 3,468
Update:
First pic: Trenched through nearly solid caliche under a few inches of soil and idea of visibility
Second pic: deeper loam above a layer of clay.
I completed the first leg of the trenching project last week. Unfortunately, I had a lot of problems with the trencher so I didn't get to take many pictures.
So far, I am impressed with the power and speed of the Bobcat 405 trencher. Considering how hard my ground is and it was my first time using a trencher on a skid steer, I think I made good time. I trenched one line a little over 1/4 mile and several tie in trenches between 100 and 150'. I have a secondary trench of about 1/4 mile that I will do in the fall and a few more tie in trenches.

The good:

-Speed at which I can trench to 5' depth and ease of use. I was surprised how easy it was to learn.
-High flow trencher has plenty of power at only 2100 rpm engine speed
-Trenched through solid limestone, hard caliche, and dense, hard-packed clay.
-More of a loader feature but ability to dial in speed to 25% for smooth operation
-Hydraulic side-shift feature
-Dual augers really do move the material away from the hole quickly
-Surprisingly good on fuel even though it is a high flow attachment

The Bad:

-Visibility. Trencher is wide and blocks a lot of my view
-Vibration in loose rock- Felt like I was running an impact hammer until I dialed down engine RPM and let trencher settle in.
-Chain came off three times. Hurt my back getting it back on WITH the help of my excavator and binder straps
-Lost almost all standard bullet teeth. Bobcat sales rep brought me a different style tooth and they seemed to stay in the pockets better
-Cups broke where there was hardfacing. (heat issue?)
-Sheared 4 grade 8 bolts on bullet teeth holders and another bent
-Hydraulic side-shift feature. Have to leave the cab and pull lever on valve block then get back in the cab to side-shift. Seemed to move on its own and that is one possible cause of the chain coming off. Broke two 3500 lb straps trying to keep boom in the middle. Finally just moved it all the way to the right side and left it there but it worked better in the middle.
-Boom length. I wanted 5 foot dig depth but it ends up being about 9' long in total. Makes hauling difficult and I am fairly certain that extra foot is causing extra vibration and play which leads to more machine vibration and may be another factor in losing the chain. Shop may shorten boom to 4'.
-Chain tensioner location. Not thought out well.
-Trench cleaner (fits on top and flips down) got loose immediately so I removed it as well as a guard that a tooth caught and bent.

I had a weld break on the right side auger guard. Thinking the side shifting put too much pressure on it while I was trenching. Though it looks beefy where it attaches to the frame with bolts, I can see where the welds were not adequate between guard mounting plate and guard. This attachment weighs about 2k lbs. Everything needs to be heavy duty and I obviously found the weak points.

Overall, I am impressed with the power. Bobcat is going to help me figure out why the chain kept coming off (tension was fine) and get the kinks worked out of it. My dealer was responsive to my concerns and said they would help me get it right. I was disappointed, though, that one suggestion is to shorten the boom. I am sure I paid more for a longer boom and was hoping that it would work as advertised but the conditions we have here can be fairly extreme for most types of digging. Seems to me that the front roller should have teeth but it's a smooth wheel. With the vibration and a spring inside the boom, it's conceivable that it bounces enough to loosen tension enough to throw chain. I can't describe how much it sucked to put that back on in the woods. Maybe shortening will work and I have the excavator to dig deeper if necessary.
Thoughts from those who have used a skid steer or ditch witch style chain trencher?

For those that are curious, I will update more when I get it back and have a chance to use it.
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