August 15, 2014

In a few posts including July 17 2014 I explained how I hold sloppily machined parts from the constant loosening.  Instead of using the supplied set screws I use hardened bolts and tighten them until the heads snap off.  The problem with correcting weak links on a machine with dozens of them is the failure happens at another weak link. 

Today’s failure fell in between 3 strengthened weak points.   The Husqvarna Blue Bird Bed Bug was being used as a dog fence wire installer.  We were using an experimental blade provided by the blade manufacture. So far this blade has been free of the bending and breaking of the Husqvarna supplied blade. This failure was the 3/4 inch mild steel drive shaft that broke at the blade mounting hub.  With our broken bold fix of the hub and the sprocket this is the next weakest point.  On most other brands the blade drive shafts are made of reinforced 1” steel, while Husqvarna Blue Bird only uses ¾ inch steel. 

We were able to save and reuse both the hub and the sprocket for only one reason; our tightening procedure kept both parts from loosening and wearing.  Cost of the repair was about $60.00 including the labor. 

  

However the customer refused to use our back up machine and blamed the breakage on our poor maintenance.  He might have felt differently if he knew the Bed Bug’s drive was rebuilt 2 rentals ago.  I would classify this customer as one who will never be back. 

July 17, 2014 Update

The customer’s complaint on the Bed Bug we normally keep set up for bed edging quit working.  A quick inspection revealed the tin idler sprocket failed and the chain came off the drive sprocket.  This Husqvarna Blue Bird Bed Bug would get a “Tractor Supply” solid steel sprocket.  The Husqvarna supplied cheap tin idler sprocket has been a constant point of failure across the Husqvarna Blue Bird line of products. 

We have used the “Tractor Supply” solid steel idler on Blue Bird Aerators, Sod Cutter and our other Bed Bug without a single failure.  This Bed Bug would also get the broken bolt replacement of set screw failures.  We have tried to keep set screws from loosening by using thread locking glues, and doubling up set screws with no success.  The machining of the shafts, hubs and sprockets are too sloppy for set screws to hold.  Our fix for the constantly loosening set screws is to use a 5/16 hardened bolt that is torqued to a point of breaking. This has solved much of the sprocket and hub loosening that we see on Bed Bug Bed Edger’s.  

In completing the repair we found a defective weld on the Blade we replaced in June. Half of the weld on a center tooth shows no penetration into the steel.  The Blade is made by a New York state Manufacturer; warranty claims on defective blades always fall on deaf ears.  The Manufacture claims they are not responsible because they supply blades built to Husqvarna specs.  Husqvarna is just a wasteland of incompetence.  

Cost is another $200.00 blade, $20.00 Tractor Supply Idler, $20.00 for a new chain and miscellaneous hardware. Total cost of repair with labor $300.00. 

June 4 2014 update

This particular blade broke on its third rental.  One tooth was torn off the tooth next to it was almost completely torn off and a third tooth has a slight crack a fourth tooth has a very tiny crack.  The vibration loosened the hub and the blade and blade hub came off the drive shaft. Fortunately the blade enclosure held the blade within it.  As describe further down in the posts if the blade hub was ether a one piece design or welded together the blade would not have separated from the drive shaft.

Cost is one more $200.00 blade and $40.00 labor to remount the hub. 

This is the first Blue Bird Bed Bug report of the season.  Both machines were serviced during our winter maintenance program.  On one machine we needed to replace a clutch cover gasket that failed to the overheating of the clutch oil caused by too small of a clutch for the application. 

On the first rental of the season blade and hub detached from the drive shaft.  The drive shaft hub assembly is one of the weakest links on the machine.  This hub shaft and bearing assembly needs a major strengthening as I referred to on May 26^th of 2013. The Blade Shaft needs to be 1” in diameter with stronger and wider bearing support.  The Blade shaft and hub assembly are sloppy loose right out of the box.  This assembly needs to be a one piece unit or at minimum machined too much tighter tolerances. 

  While Jody Kerr of Blue Bird believes it is too expensive to fix this problem a simple tightening of the tolerances would only require an adjustment on the boring machine that bores the blade hub.  At the Rental Show I passed out the address to this Blog to Jody Kerr and some members of her staff.  

One of the issues is the two small set screws that hold the hub to the blade.  The set screw wrench will break before the desired torque is reached.  I have come up with a solution to try to solve the problem with blades and hubs flying off.  I replaced the set screws with grade 8 bolts.  I torqued the bolts until the heads break off.