Several parts modification methods for the Caterpillar CAT950E loader

The Caterpillar CAT950E wheel loader is a product from the early 1990s in the United States. It is equipped with a 3304 Caterpillar engine, which is powerful and has a low failure rate, making it suitable for various construction projects. This model is relatively rare in China and is facing the risk of being phased out. Therefore, it is quite difficult to purchase accessories for this model. Generally, orders have to be placed abroad, which leads to a long purchase cycle and high prices. The following introduces two types of parts modification and repair experiences for this model.

1. Modification of exhaust gas turbocharger

The current market order price for this model of turbocharger is around 15,000 yuan, and the delivery cycle is approximately one month. Due to the tight construction time and heavy tasks during the flood season, the machinery cannot be idle for a month. Therefore, we are considering using domestic parts to replace imported ones for modification. The technical conditions are: The power and load are comparable to those of this machine, and the external dimensions are about the same. Try to minimize the modification of machined parts. The load of automobiles is smaller than that of construction machinery, so the turbochargers on automobiles are not considered. The dimensions of the turbochargers on domestic construction machinery such as Shantui and Huangtui are quite different from those of this machine. Finally, a turbocharger of the Shangchai 6D114 engine used in road rollers was selected, and its power and load are comparable to those of this machine. The shape and size of the exhaust gas inlet of the turbocharger are the same. The shapes and sizes of the oil inlet and return pipes are the same as well. The size of the air pipe is a little larger than that of the original machine. You can replace it with a hose. The connection port between the turbocharger and the muffler is different from that of the original machine. A pipe clamp needs to be machined to connect the turbocharger and the muffler, and the problem will be solved. This modification process is simple, the fault handling cycle is shortened, and the price is cheap and practical. This kind of turbocharger is about 2,000 yuan.

2. Modification of air compressors (air pumps)

The braking system of the entire wheel loader relies on an air compressor (air pump) installed on the engine to provide air source control. If the air compressor (air pump) malfunctions and cannot pressurize air, the entire machine cannot be started. Low air pressure leads to poor braking performance and poses a safety hazard. The air compressor (air pump) has been working under high temperature and high pressure for a long time. The cylinder liner, piston, piston ring, and intake and exhaust valve capacity wear out, causing faults such as the machine being unable to press air, difficulty in pressing air, and severe oil consumption. Therefore, the air compressor (air pump) needs to be repaired. At present, the order unit price of this model of air compressor (air pump) on the market is about 9,500 yuan per unit, and the purchase cycle is approximately one month. Moreover, when purchasing, only the complete assembly can be bought. Generally, some small accessories such as piston rings and intake and exhaust valves cannot be purchased separately. Therefore, we are considering using domestic parts to replace imported ones for modification. According to the measurement, the cylinder diameter of the original air compressor (air pump) was 86 mm, and the piston rings were two gas rings and two oil rings. It is understood that the cylinder diameter of Jiefang brand cars is 87mm, and the piston rings are also two gas rings and two oil rings. In response to the above situation, we have determined two maintenance plans: One is to replace the piston rings. The comparison between the piston rings of Jiefang brand cars and those of this machine is: The cylinder diameter is a little larger. The thin gas ring (Jiefang brand piston ring) is too loose when installed in the piston ring groove of this machine, and the thick gas ring (Jiefang brand piston ring) is a little tighter when installed in the piston ring groove of this machine. Therefore, two sets of Jiefang brand piston rings should be used to form one set of piston rings (the thin ring is not needed, only the thick ring is used) on the air compressor (air pump) A part of the opening of the new piston ring is ground off to make a cylinder diameter of 86mm. The original piston ring groove is machined by a lathe according to the thickness of the new ring. The second method is to enlarge the original cylinder diameter to 87mm, and use Jiefang brand pistons and piston rings. The Jiefang brand piston pins are smaller than those of the original machine. Then, the piston pin holes can be machined according to the original piston pin diameter by machining. Based on the current condition of the machine and the requirements of quality control, we adopt the second maintenance plan. It has now been in use for over 4,000 hours and its mechanical performance is good.