[Restoration] Repair the Kubota U-30-5 mini backhoe. (Kubota Yumbo) 

0:00
Hello everyone, this time we will restore the U-30-5 type manufactured by Kubota, which has the world's No. 1 share in the mini backhoe. This machine has been running for 4300 hours, and there are oil leaks and defects, so we will maintain each part.
1:12
Since the counterweight weighs 400 kg, remove it using a crane.
1:55
The wheels of the engine crane have been damaged and the counterweight cannot be moved.
2:40
The bush shrinks inward by welding the "bush" into which the bucket pin is inserted.
3:07
Another way to remove the bucket pin bush is to burn it off with acetylene.
3:59
Since new parts are coated with rust preventive chemicals, remove the chemicals with kerosene or gasoline.
4:30
There is a groove on the inside of the bush, where grease collects and lubricates. The dust seal prevents water and dust from entering from the outside and discharges old grease from the inside to the outside.
5:38
The bucket pins have grease holes in place, so if you accidentally attach them elsewhere, they will cause poor lubrication. If the grease hole is clogged, heat the bucket pin to improve it.
5:49
There are three cylinders used for cutting work, and the bucket cylinder is the thinnest cylinder.
7:55
I had a hydraulic hose made.
8:41
Attach the link with a double nut, do not expose the threads at this time. If the screw thread of the bolt is crushed, the nut cannot be removed.
9:14
There is an oil leak from the arm cylinder, there is a small hole in the dust seal to drain the leaked oil from the U ring. If this hole is not opened, the dust seal will come off due to hydraulic pressure.
12:01
The cylinder head uses a "U ring" to keep the oil pressure on the rod side from leaking out, and the piston uses "three types of rings" to keep the oil pressure on the rod side and the cylinder side. If there is a leak in this part, the hydraulic cylinder will not be able to demonstrate its original performance.
12:26
Use grease that is harmless to rubber when installing the seal.
12:38
To maintain the oil pressure, shift the opening of the ring by 180 °.
12:58
As the ring deforms, use a piston ring compressor to correct it.
13:47
The U-ring is very hard, but it becomes soft when you put it in hot water, so it is easy to install.
14:38
Install the piston so that the detent ball and the dent are aligned.
15:12
Be careful not to hit the cylinder head body with the detent of the cylinder head.
15:16
It's complicated because it has a "mobile crane" device.
15:38
The boom cylinder is made thick to support the boom arm bucket.
16:40
If it is difficult to insert the bush of the rod vertically, install it using the rod as a guide.
17:23
The dust seal removes dust on the rod and prevents water from entering from the outside. Oil leaks from the inside are drained through a small hole.
17:32
A cushion is attached to the boom cylinder, which is a "thing that softens the last impact" when the boom is undulating, and cushions the impact at the stroke end by impairing the flow of oil.
17:45
The white backup ring prevents the hydraulic pressure "overhang" on the O-ring and supports the O-ring on the opposite side of the pressure direction.
18:24
The piston is detented with the ball and screw, and the detent of the screw is stamped.
18:34
It is enough to have one detent for the cylinder head.
20:01
Water the ground before painting, preventing dust from flying up and curing it.
#Details in the summary section
#Restoration
#Kubota

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