Pressure testing machine error

Cause of error
1. Error caused by incorrect installation of testing machine
The uneven installation of the testing machine will increase the friction between the moving parts, affect the vertical installation, and bring errors to the testing machine.
(1) The host part is not installed horizontally
There will be friction between the working piston and the working oil cylinder, and the guide wheel between the working platform of the testing machine and the column on one side will also produce friction, which will cause errors, which are generally expressed as positive differences, and the errors will decrease with the increase of the load.
(2) The dynamometer part is not installed horizontally
If the dynamometer is not installed horizontally in the front and back, friction will be generated between the bearings of the pendulum shaft, and the error is generally negative.
The error caused by the above two factors is characterized by large impact on small load and small impact on large load.
2 Error caused by friction resistance
(1) Friction resistance of main engine
The friction resistance of the hydraulic testing machine mainly occurs between the working cylinder and the working piston. In addition to the factors of uneven installation, there are dirt in the oil cylinder and the oil viscosity is too high, which will also cause increased friction resistance. In addition, the improper position of the guide wheel of the working platform will also increase the friction with the column on one side.
(2) Partial friction resistance of dynamometer
There are many reasons for friction resistance of the dynamometer, such as dirt between the force measuring cylinder and the force measuring piston, excessive viscosity of the oil, high friction of the driven needle on the indicator device, oil dirt and dirt on the gear tooth rod, or the upper limit of the tooth rod is pressed too tight, wear and fracture of the force measuring piston belt, etc.
Error elimination method
For the occurrence of the above errors, first check whether the installation of the testing machine is horizontal, and level the main machine in two directions perpendicular to each other with the frame level. Adjust the front and rear level of the dynamometer at the front of the swing rod, align and fix the edge of the swing rod with the inner scribed line, and adjust the left and right level of the body against the side of the swing rod. The internal dirt of the oil cylinder can be drained and cleaned, and the oil with proper viscosity can be replaced. The friction force of the driven needle of the dynamometer indicator device is too large, and the gear rod is too dirty. Use gasoline to clean and adjust the compression screw and the upper limit of the rod, and replace the belt on the force measuring piston. These can achieve the purpose of eliminating errors, so that the testing machine can reach the qualified use state