SEBO M4 Nut, DIN 562, for M4 Fastenings — Single

A screw only clamps when something on the far side holds the thread, and on SEBO machines that job often falls to this small nut. Part 131 carries the designation M4, ST, DIN 562 and is sold one at a time. DIN 562 is the standard for the thin, unchamfered square nut, and the square shape is what lets it drop into a moulded pocket in the housing and stay put while the screw is turned from the other side.

Nuts vanish into the bench during a teardown, and one that has been cross-threaded leaves the screw spinning without ever pulling the joint tight. A nut rounded at the corners by pliers is the other common casualty, because once the flats are gone it can turn in its pocket and the fastening can no longer be tightened at all. Clean threads on both halves are what make a fastening hold.

• Part number: 131
• Thread: M4
• Designation: M4, ST, DIN 562
• Form: thin square nut in steel
• Quantity: one nut
• Ten-pack version: part 0131ER, the same M4 DIN 562 nut in a set of ten
• Pairs with: M4 screws used on SEBO vacuums, including the AM4 x 12 in part 0117ER

Check the thread against the fastener it mates with before ordering, since a machine can carry more than one thread size and the nuts are hard to tell apart by eye. If the repair calls for several, the ten-pack under 0131ER saves ordering them one by one.

Fit it by seating the nut in its pocket first and then starting the screw by hand from the other side. Forcing the screw in with a driver before the threads have met is what produces the cross-threaded nut that has to be replaced next time, and on a captive nut sitting behind a panel that mistake is not visible until the joint refuses to tighten.

Useful search phrasing includes SEBO M4 nut replacement, DIN 562 square nut for a vacuum and genuine SEBO 131. Genuine SEBO hardware from an authorized dealer, shipping in 2-5 business days.