The original radial gap value of Roots blower bearing is determined according to the accuracy grade of the bearing. If the outer end of the impeller is found to rub against the casing, remove the fan gear box cover, loosen the bolts on both ends of the fan housing, and remove the locating pin. Put the outer diameter gauge on the drive gear and the pulley (or coupling) at the other end.
Gently and symmetrically strike the gear and the belt pulley (or coupling) at the other end with a copper hammer. Measure with a feeler gauge every time you tap. Repeat until the clearance meets the requirements, and then tighten the shell bolts at both ends symmetrically. If it is found that the end face of the impeller rubs against the side wall plate of the casing, the clearance between the impeller and the side wall of the casing can be detected with a feeler gauge, the screws for fixing the bearing cover can be pulled out, and padding paper can be added or extracted between the bearing seat and the bearing cover near the belt pulley (or coupling) end to adjust, so that the impeller can move axially. Depending on the measured clearance.
1、 Because Roots blower It is a constant flow fan. The main working parameter is the air volume. The output pressure changes with the change of pipe and load, and the air volume changes little. 2、 Principle: Roots blower is a positive displacement power machine. Two impellers are driven by a pair of synchronous gears to rotate in the opposite direction. The intake and exhaust ports are separated by the "meshing" of the impeller profile (there is a certain gap between impellers, and they do not contact each other), and the inhaled gas is moved from the suction port to the exhaust port without internal compression, At the moment of reaching the exhaust port, the high-pressure gas at the exhaust side is pressurized and transmitted to the system to do work due to backflow. The periodic suction, exhaust and instantaneous constant volume compression cause the pulsation of gas flow velocity and pressure, which will produce large aerodynamic noise.
3、 Disassembly 
1. Precautions during disassembly (1) All connectors and inserts shall be engraved with matching marks, especially the gear. (2) Do not damage the parts, especially the mating surface. (3) The thickness of all gaskets shall be measured during disassembly. (4) The disassembled parts, especially the bearings, shall be protected from dust pollution. (5) Appropriate removal tools shall be used. (6) The newly stopped fan must wait for the body and lubricating oil to cool before it can be disassembled to avoid scalding. 2. Disassembly steps: remove all accessories from the unit - drain the oil in the gearbox - remove the pulley - remove the gearbox and adjusting screw - remove the gear - remove the bearing cover - remove the wallboards on both sides of the casing.
4、 Assembly of Roots Blower 1. Precautions during assembly (1) Check whether the disassembled parts are damaged. Pay special attention to the matching parts. If any damage is found, repair or replace them. (2) The bearing shall be cleaned and then coated with lubricating oil. When installing the bearing, tools, hands, etc. shall be cleaned. (3) Thoroughly remove the dust from the fitting part, and then apply oil. (4) If the sealing gasket is damaged or lost, the gasket with the same thickness and material shall be replaced.
2. The assembly step (1) is to install the wall panel (front wall panel) on the drive side to the housing. (2) Install the impeller part into the casing from the gear end. (3) Install the gear end wall plate on the casing, pay attention to the total axial clearance, and select the casing gasket if it is not enough. (4) Assemble the front and rear bearings. When assembling the front bearing, the bearing housing shall be filled with 1/2-1/3 bearing space grease. (5) Assemble the gear. (6) Install the drive side bearing and lock nut together, and install the bearing gland. (7) Adjust the clearance and drive the locating pin. (8) Install belt pulley and other parts.
5、 Clearance adjustment of roots blower
1. Adjustment of casing clearance: it is ensured by the locating pin hole between the casing and the wallboard, because the locating pin hole must not be damaged when disassembling the fan. Impeller casing 0.20-0.395
2. Adjustment of impeller impeller clearance: turn the impeller to the clearance schematic position, align the driven gear with the driving gear mark and press it onto the shaft, successively install the gear retainer ring, stop washer and lock nut, and slightly tighten the lock nut. Try to rotate the impeller for one circle. If it can't rotate, rotate the impeller to make the contact point on the top. Tap the impeller clearance with a copper bar to make the cone of gear and shaft move relatively, so as to adjust the impeller clearance. When the impeller impeller clearance meets the specified value, lock the gear. Impeller - Impeller 0.29-0.34
3. Adjustment of axial clearance between impeller and wallboard: when assembling wallboard, ensure the total axial clearance C+D (adjust the thickness of casing gasket), and then adjust the axial position of impeller through four sets of adjusting screws on the front wallboard to ensure the distribution of clearance C and D at both ends. Impeller front wall panel 0.12-0.18 Impeller rear wall panel 0.63-0.69 When tightening the adjusting bolt, the pressing plate bolt should be loosened, otherwise the adjusting bolt will be damaged.
