The installation and adjustment of the backrest tension rod affect warp tension and weaving stability. On air-jet looms with upper and lower warp beams, the upper backrest tension rod assembly may include a tension rod with short and long arms, connecting rods, a spring, a spring seat, a support rod, a tension sensor, and associated mounting hardware.
The components should be assembled in the correct sequence before the backrest's longitudinal and vertical positions are adjusted. The exact assembly and adjustment procedures must follow the structural drawings and maintenance manual for the specific loom model.
Installing the upper backrest tension rod
Prepare the components
Before installation, confirm that the tension rod, short and long arms, connecting rods, spring, spring seat, support rod, tension sensor, eye ring, pins, nuts, and other required hardware are available. Check the mounting points for deformation and abnormal wear.
Connect the linkage to the tension arm
Use a pivot pin to connect one end of the connecting rod to the tension arm. Connect the other end to the shaft hole at the end of the tension rod's short arm. After assembly, check that the joint moves freely without binding.
Mount the tension rod
Pass the pivot pin through the central connecting hole of the tension rod and mount the rod at the upper end of the tension shaft support. Confirm that the pin is correctly positioned and that the rod moves as intended by the mechanism design.
Install the support rod and spring seat
Insert the upper end of the support rod through the hole at the end of the tension rod's long arm and secure it with a nut. Install the spring seat at the lower end of the support rod and check that the connection is secure.
Fit the spring
Place the spring over the support rod so that one end rests against the spring seat and the other end contacts the tension rod. The spring orientation and seating must match the machine design. Make sure that the spring is not tilted or incorrectly positioned.
Install the tension sensor and eye ring
Mount the tension sensor below the spring seat and connect its other end to the eye ring. Use a pivot pin to attach the eye ring to the designated tension support. Check that all connection points are secure.
Adjusting the longitudinal position of the backrest
This procedure applies to certain loom models with a corresponding screw adjustment mechanism. Confirm that the machine has the same structure before following these steps.
Install the adjustment screw assembly
Fit the adjustment nut to the connecting plate assembly and secure it with screws. Thread the adjustment screw into the nut, then install the adjustment screw seat. Rotate the adjustment screw to the required locating position according to the mechanism design, and secure the screw seat to the side plate with screws.
Fit the two small round nuts to the adjustment screw. Repeat the installation on the opposite side, following the machine's structural drawing.
Move the backrest forward or backward
Loosen the four corresponding nuts on the left and right sides of the loom. Rotate the adjustment screws on both sides to move the backrest to the required longitudinal position.
Once the target position is reached, retighten all loosened nuts. Check that both adjustment assemblies are secure and that the backrest cannot shift during operation.
Adjusting the vertical position of the backrest
Loosen the locking nuts
According to the machine structure, loosen the four nuts and four stud nuts on the left and right sides of the loom to allow the required vertical adjustment.
Adjust the backrest height
Use a wrench to turn the upper and lower adjustment studs as required. For upward adjustment, the lower end of the stud presses against the specified surface within the connecting plate assembly and raises the backrest. For downward adjustment, loosen the stud and allow the backrest to descend under its own weight.
During lowering, provide appropriate support for the assembly and keep hands and other body parts clear of potential pinch points. The adjustment direction, stud locations, and support method must follow the machine design.
Secure the assembly and inspect the position
After reaching the required height, retighten all nuts loosened during the adjustment. Check that the backrest is positioned consistently on both sides and that all connections are secure.
After adjustment, inspect the backrest position, warp tension, and the operation of the associated mechanisms according to the maintenance manual. If the tension sensor or electronic warp let-off control system is involved, carry out the required calibration and verification procedures specified by the manufacturer.
Precautions during adjustment
Before maintenance or adjustment, stop the loom and isolate its energy sources according to the operating procedure. Confirm that moving components cannot start unexpectedly. Before and after adjustment, inspect the pivot pins, nuts, spring, and sensor connections. Do not start the loom while critical fasteners remain loose.
The longitudinal and vertical positions of the backrest affect the warp path and tension. Record the original settings before making changes, adjust them in stages, and verify the results through the specified checks or a trial run. Adjustment references, tolerances, and tightening requirements vary by model and must be taken from the original maintenance documentation.
Custom machining of precision components
When the backrest tension rod assembly, connecting rods, support brackets, or other mechanical parts require non-standard replacements, Hansheng Automation provides single-piece and small-batch precision machining based on customer engineering drawings. Our drawing-based machining services also cover components for tobacco packaging machinery, filling equipment, yacht equipment, and remote-controlled racing cars. Specific machining requirements are determined by the supplied drawings and technical specifications.
