Construction machinery parts repair tips summary

1, bulldozers frame welding repair station
After six years SH320 bulldozer used trailer chassis in different directions due to the long moment and the role of torque, the two Semi-mobile crushing plant bracket bolts fracture occurred, plus they

did not discover, leading Taiwan frame forearm broken into two. As difficult to repair, and that even if they have to buy the old pieces of more than 10,000 yuan, for which we

decided to use welding techniques to repair.
In practice, the first in accordance with the status quo will be broken bolts installed, the platform frame is assembled, will crack first spot live round vibration screen, then

remove and back to the workshop, with the bracket set up 30cm, within 1m around the crack heating with charcoal (to prevent local thermal deformation), to reach about 120 ℃,

and then use acetylene flame cutting out the V-shaped groove, groove depth of the arm-thick 3/4, and then the implementation of welding.
Welding process is as follows: DC arc welding machine, reverse method (weldments then negative), J507 electrode (heated before use to 100 ℃), electrode diameter Φ3.2mm, arc

welding current situation according to regulation. After welding, eliminating stress (heated to 200-300 ℃ slow cooling) and for grinding process. After welding machine use that

quality fully meet the requirements. The machine has been used 10 months, working properly.

2, the loading mechanism Power Units
Loaders use more gas assisted hydraulic dual circuit braking system, a KLD85Z loaders company also adopted this braking system. Because long-term use, once the brake booster

sudden failure during use, check the cause of the failure is: booster cylinder chambers prolonged exposure to brake fluid corrosion and pitting, leading rubber cup wear and

failure.
Upon inquiry, this product is no domestic parts, import price of 12,000 yuan. Obviously, if the purchase is not economically viable. Found BJ2020-type jeep Clutch bag rubber cup

cup size with this machine similar, but slightly smaller diameter. Reanalysis piston chamber size, consider that this piece perfectly usable lathe; using rapid small amount of

feed processing electromagnetic shaker, in order to reduce the roughness of the cavity; adjust the feed turret 2-3 degrees, so that there is a certain oblique wall degrees;

diameter outer diameter dimensioned according cups, and more than its original size small 0.4-0.5mm. After careful measurement processing, repaired completely normal use.

3, the engine cylinder head deformation Repair
A company of two Kawasaki KLD85Z type loaders, its long-term work in the engine cylinder head temperature, high pressure, heat load and alternating loads and warpage, cylinder

head gasket washed out from the water at the crossing, causing the combustion chamber pressure drops lack of engine power and the water coming out the radiator filler neck.
Continuous cylinder head gasket replaced twice, each for one month after it was washed out. Dismantling the unit and found the cylinder block, cylinder head are deformed.

Cylinder block flatness error of 50μm, also meet the technical requirements, but the cylinder head flatness error can reach 0.20mm, this variant was washed out of the cylinder

head gasket is the main reason.
Using the repair method, since the machine is covered with no concave chamber, without regard to changes in volume combustion (combustion chamber volume changes in the value

generally should not exceed 4% of the original volume), using the method of processing of the face milling head plane; joints in the cylinder head and the cylinder is installed

at the water crossing a copper pad (pad thickness of the copper water crossing 1.2 times the thickness of the concave Taiwan), instead of the rubber seal cylinder pad, then

install the cylinder head gasket large round shaker, while using the first post-cold-hot tight tight approach sturdy cylinder head bolts. With this method repair of the engine,

and then not to overshoot the cylinder head gasket failure.

4, dump truck repair welding consumables
Czech companies have produced a type of self-T815 tanker of 30 units in use in a few years found that due to the localization of the car chassis parts, chassis quality can not

meet the construction requirements, certain accessories are often malignant fracture, giving users great economic losses. After a long journey, the aircraft wearing parts (eg

steel lugs, steel clips, spring steel and axle casing, etc.) carried out repair welding, and achieved good results. When the welding Note: Use the DC arc welding machine, J506

welding, preheating before welding, after welding, insulation, elimination of local thermal stress and prevent stress concentration.

5, dry cylinder liners for emergency repairs
A company of a Komatsu WA420 wheel loader, because the long-term work in the field, using the engine cooling water containing minerals more bucket elevator, combined with the

cooling system filter maintenance negligence cylinder engine crankcase II took place in cavitation, while making the thin-walled cylinder is also cavitation, there Φ2mm size

holes, resulting in the crankcase sump water. Taking into account the aircraft equipment purchased in 1992, the engine crankshaft, camshaft and cylinder used at or near the

limit, invested a lot of money for repair of no value, but the engine's cylinder and piston wear still meets the technical standards, no burning oil and black smoke, and the

engine is working properly, no significant increase in fuel consumption, hydraulic systems and chassis parts continue to use, and significantly higher than the domestic similar

mechanical efficiency.
To this end, we have the original liner turned 180 degrees, and in the crankcase cavitation at blocking with AB glue, and then reassemble the engine running again shows that

working properly. With this lesson, later working properly. With this lesson, in a later work, management and maintenance staff very seriously cooling water filter maintenance.

Has been a year since the restoration, the aircraft still in use.