Friday, April 22, 2011
I am only sharing my experiences, machines are dangerous and I can be seriously injured or killed trying to operate them. Remember, I don’t start an engine unless I am sure I know how to stop it! I do not try to do the procedures that I describe unless I am very familiar with the machine I am inspecting and have a working knowledge of the operation. I am not an authority on the topic, I do machinery inspections at my own risk.
Thursday, March 31, 2011
Check that Loader Backhoe Part 1
I have been involved with the loader backhoe business since 1986, I don’t consider myself an authority but I have inspected over 500 different backhoes. I used to do the purchasing for several other dealers at the auctions, inspecting 10 to 20 backhoes at one time. The opportunities to discover the many problems involving the loader backhoe were magnified at the auction because of the many rough machines band aided and dumped in the auction . I will touch on several of the more common areas of trouble that I have experienced. I am more familiar with and have owned the common name brands of Case, Deere, JCB, Caterpillar, Terramite and Kubota. I also have owned a handful of Earthforce, Bobcat, Allman and Ford New Holland.
I am only sharing my experiences, Machines are dangerous and I can be seriously injured or killed trying to operate them. Remember, I don’t start an engine unless I am sure I know how to stop it! I do not try to do the procedures that I describe unless I am very familiar with the machine I am inspecting and have a working knowledge of the operation. I am not an authority on the topic, I do machinery inspections at my own risk.
Bucket, Loader arms, loader cylinders, loader pins and bushings
Starting at the front of the machine and working my way back I start with the very tip of the loader bucket, is there a bolt on cutting edge, if so has it been worn back to the original edge and if so can it be flipped. I will refer to an earlier paper that I wrote about buckets and quick attach plates, located on the website titled, “Check that skid steer loader bucket and quick attach plate” The existing edge of the loader bucket should be straight, not bowed up or down, the corners should not be braced or welded unless it is the original factory welding. Replaced edges and side cutters are ok if the welding has been done by a professional welder. If the edge is worn back, or if it has been welded or bowed it is usually weak and will affect grading, it could be an expensive repair to renew it. The bucket bottom should not be distorted or broken through and the sides of the bucket should be straight. The back lip of the bucket should not be bent, I frequently find back lips bent forward and down because of chain lifting too heavy of a weight. The damage is done by attaching a chain to the back of the bucket, draping it over the front of the bucket then rolling the bucket back to lift with the tilt cylinders. This damage can affect the capacity and weaken the bucket. Some loader buckets have the top lip designed as a grading edge, if it is bent or distorted then it will make a poor grading edge. When I am in the machine I will raise the bucket off of the ground a couple of inches then roll the bucket forward and tap the ground with the cutting edge this will show me the play in the loader pins and bushings from the loader tower to the bucket. If there is excessive play at the pins and bushings further investigating is necessary to tell if the bosses are worn out or if just pins and bushings will fix the problem.
I will inspect the loader arms at this time, making sure there are no welds, cracks and also pin and bushing play. There are usually 3 or 4 hydraulic cylinders to inspect for leaks and bushing play. If there is a leaking lift or tilt cylinder I will look further for a scored or bent ram (chrome section). A scored ram will definitely increase the cost of repairing a leaky cylinder. A bent or badly scored ram will have to be replaced. A welded or repaired loader arm is definitely a reduction of value, true, it might be stronger than new, but it is frowned upon by perspective buyers and a sign of abuse. I will raise the loader all the way up as well as roll the loader bucket all the way over to make sure that the hydraulics operate normally through the full cycle. (I make sure that there is nothing in the bucket because it is going to fall out!) The arms should not rub the sides of the tractor during the cycling if they do then there is a sign of loader arms being twisted. I will also spend some time trying to tell if the loader arms are twisted in any way, a bucket cutting edge that is worn on one side more than the other is a sign of a possible twist in the loader arms or possibly a low tire. With the loader arms all the way down, I will look for a reference point on the tractor to see that one side is the same distance as on the other side of the tractor, (not the front axle, it can pivot, one side might be higher than the other). Many times I will use the hard nose (housing around the radiator) to measure the distance between it and the loader arm on each side of the tractor. I am careful to watch that when I raise the arms that they raise evenly, it is possible to power the loader arms down so that a twist comes out momentarily. When the loader arms are not powered down they may show the twist. I always spend a lot of time looking for weld repairs at the cross bar, the section of the loader in front of the grill that ties the sides of the loader arms together. A welded cross bar is an indication that the arms should be checked for a twist and the loader has been pushed beyond its capacity.
It is important to note that when raising the loader arms the hydraulics should be smooth operating. The operation should not be jumpy, slow or noisy. Loud squeaking could indicate a dry pin and bushing that is out of alignment or starving for grease. Jumpy or slow operation indicates hydraulic problems, possibly a bad hydraulic pump or filter. A loud squealing can be coming from a relief valve that is not too alarming however a squealing hydraulic pump can be very expensive to repair.
The loader tower is the area where the loader arms and lift cylinders are mounted to the tractor frame with pins and bushings. The tower should be inspected for cracks and welded repairs. The tower is mounted to the main frame of the tractor so I look for main frame cracks and repairs in that vicinity. On some machines this area can also serve as a hydraulic oil tank so an oil leak in this general area can be an indication of a crack. Once again there are pins and bushings in this area to observe as I tap the ground with the cutting edge.
Front Axle, Differential, Tie Rods
I will inspect the front axle for trunion play on a 4 wheel drive or king pin play on a 2 wheel drive model. Bushing play in this area lets the front wheel camber change as the weight is lifted off the ground by raising the tractor by powering down with the loader arms. Play in either 2 or 4 wheel drive models is very expensive and needs to be considered. I look for leaking at the front axle seals, oil running down the inside of the wheel and tire is a good indication of a leaky planetary hub seal, oil running down the bottom trunion could be a sign of a outer u-joint differential seal. At the same time I check the tie rod ends by rocking the steering wheel back and forth to observe the play in the ball sockets of the tie rod end. Usually there is a hydraulic steering cylinder to check for play as well as leaks. Lastly there is usually a long tie rod between the front wheels to check for bends, if it is bent it might be near impossible to adjust the toe of the front alignment.
Look for “Check that Loader Backhoe part 2” for information about how I check the Drive Line, Outriggers, Brakes and Backhoe.
Wednesday, December 2, 2009
Wednesday, May 14, 2008
Let me start this with an explanation of why I even thought it might be useful to put this detailed process out there for anyone to read. There are many reasons but the most obvious is that there are a lot of Bobcats out there with cabs. The front door is destroyed because of people raising the loader arms with the door open, it knocks the door off the hinges and either breaking the glass or damaging the whole door so that it requires repair with a new glass. My position as a used equipment dealer means that I get those Bobcat skid steer loaders with the empty door frame, broken glass, or nothing at all where a door should be. I have had 2 door frames in the past month requiring the glass installed, one I took to a glass shop (not specializing in machine glass obviously), $95 bucks and 2 days later I got it back with a hint of “don’t come back”.