Varillas de conexión

The connecting rod is one of the most important components in the frac pump power end, which must be strong enough, but not too large in size and weight.

The connecting rod parts are composed of the connecting rod body, connecting rod bearings seat, bearing cover, bearing bush, bushing, connecting rod bolt, and other parts. The small end of the frac pump connecting rod is connected with the crosshead by a crosshead pin, the big end of the con rod is connected with the crankshaft journal. The big end hole and the small end hole are respectively installed with bearing bush and bushing.

Normally, The connecting rod body and the bearing seat, connecting rod bearings seat, and connecting rod bearings cover are made into separate structures in order to assemble and disassemble parts and adjust the bearing gap easily. And they are connected by connecting rods bolts which form a whole.

The connecting rod is a moving part that transmits power at the frac pump power end. It converts the rotational movement of the crank into the reciprocating movement of the plunger.

Usually, the connecting rod manufacturers made the conn rod by casting, then blasting the casting, and machining the full dimensions completely.

It is critical that the center lines of bores must be parallel. Material heat treatment and nitriding treatment must also be done with great care to achieve qualified mechanical properties.

The connecting rod parts are subjected to fluctuation and impact load, the most common type of material that the connecting rod manufacturers use is 4340, which has high fluctuating strength, tensile strength, rigidity, and high damping factor.

With the development of fracturing pumps in the direction of large displacement, high power, and high pump pressure, the working environment of the connecting rod parts is getting worse and worse. When fracturing pumps work, the connecting rod and crankshaft are required to have high strength and fatigue resistance. Ensure that the pump can work continuously and reliably in multiple stages under the conditions of large displacement, high power, and high pump pressure.

The connecting rod bearings are subjected to alternating tensile and compressive stresses and bending stresses during work. Therefore, the con rod is prone to fatigue fracture in the high-stress area when working under a complex stress state.

During work, it is subjected to alternating loads such as tension, compression, and bending, as well as the pulsating action of the fluid in the pump, which tends to produce large vibrations and cause fatigue failure of the connecting rod parts structure.

Thus, the connecting rod parts require high strength and fatigue resistance, which can ensure the frac pump can operate continuously and reliably in multiple stages under the conditions of large volume, high power, and high pump pressure.

The connecting rod parts fastened around the crankshaft on one end and to the crosshead on the other end. As the crankshaft turns, the power end connecting rod also turns, forcing the plunger up and down. A bad connecting rod or rod bearing will eventually destroy the power end.

After analysis, it is generally considered the vulnerable parts of the connecting rod and crankshaft are the parts that connect the connecting rod bearings seat and the bolt. According to the statistics formed by the experts, the circling number of the alternating load that the connecting rod parts can withstand is 1.68*10⁸, so the estimated working life span of the connecting rod would be around 500 hours.

It is just an estimated life span, you can take this time as a limit to check the connecting rod. And we believe that if the connecting rod manufacturer carburizing and nitriding the connecting parts can extend the working time.

Firstly, we suggest that you should check the con rod every 500 hours if it is new. If there is no crack or deformed, the power end connecting rod can work still. But please check it every 100 hours since then.

Secondly, make sure the lubrication works are done pretty well. It is critical.

Thirdly, make sure your power end connecting rod is precisely matched with your frac pump. As we know the fluid end is formed unified, however, the power end parts vary according to the site requirement. It is known that a conventional connecting rod is a single unit. Multi pieces of the connecting rods have been developed as a substitute for the one-piece rods. What we are using now is usually separate to the connecting rod body and the connecting bearings seat, bearing seat, and bearing cover. The separate structures would make the assemble and disassemble parts and adjust the bearing gap easily. Please note that no matter one piece or multiple pieces, the wear tends to occur at the junction between the jointed pieces, check these parts carefully when maintenance.