Screw M12x45

Screw 40504 is a socket head cap screw M12x45 manufactured to DIN 912 in strength class 8.8. The cylindrical head with hexagon socket allows installation in locations with restricted access, where an open-end or socket wrench cannot complete a full rotation. Class 8.8 means a tensile strength of 800 MPa and a yield strength of 640 MPa – values appropriate for structural connections subject to vibration and dynamic loads typical of pressure washer pump and motor operation.

Application

The screw is used when assembling structural components of Kranzle pressure washers where a specified tightening torque and hex key access are required. The 45mm length and M12 thread indicate a connection carrying significant loads. Verify the exact installation point from the disassembled machine or the service documentation for the specific model.

Symptoms – when to replace

• Damaged or rounded hexagon socket in the head – the hex key rotates without gripping, and the screw cannot be removed or tightened in the standard way.
• Visible corrosion on the thread or shank – particularly in connections exposed to working water and detergents, which accelerate corrosion of uncoated steel.
• Damaged thread – the screw does not run in smoothly or the thread in the hole shows play after tightening to the nominal torque.
• Cracking or deformation of the shank – visible to the naked eye after removal, particularly in connections transmitting motor vibration.

How to select the right part

Three parameters must match simultaneously: thread M12, length 45mm and strength class 8.8. The length of a DIN 912 screw is measured from the underside of the head to the end of the shank – it does not include the head. Before ordering, measure the shank length of the removed screw with a calliper, not the total length including the head.

Class 8.8 is not interchangeable with class 4.8 or 10.9 without verifying the required tightening torque for the connection. A class 4.8 screw of the same geometry is significantly weaker – it may deform at the torque specified for class 8.8. A class 10.9 screw is stronger, but requires higher torque and a different approach to thread locking.

Identify by reference number 40504 – for standard screws, the Kranzle catalogue number is a more reliable basis for selection than independently finding an equivalent in a standards catalogue, as the manufacturer may have applied additional requirements regarding coating or tolerances.

Compatibility

Fastener for Kranzle pressure washers. Verify the range of application by reference number 40504 and dimensions M12x45 class 8.8 DIN 912.

[faq]

How to correctly measure the length of a screw if I need to confirm it is 45mm and not, for example, 40mm or 50mm?|The length of a DIN 912 screw is the distance from the flat underside of the head to the end of the shank – measured without the head. Place a calliper against the underside of the head and measure to the tip of the thread. The cylindrical head of an M12 socket head cap screw has a standard height of 12mm to DIN 912 – if you measure the total length of the screw including the head and get approximately 57mm, the shank is 45mm and the screw is correct.

How does DIN 912 differ from DIN 931 and DIN 933 – is it the same screw under a different name?|No. DIN 912 is a screw with a cylindrical head and hexagon socket (socket head cap screw) – the head sits recessed in a counterbored hole. DIN 931 and DIN 933 are screws with an external hexagon head (for an open-end or socket wrench) – DIN 931 with a partial thread, DIN 933 with a full thread. They differ in both head type and the installation tool required. These standard screws are not interchangeable at the same diameter and length, as they occupy different installation spaces.

How to tell whether the hexagon socket in the head is damaged enough that attempting to remove the screw with a key is not worth trying?|If the hex key enters loosely or you feel that the rounded socket does not grip at low torque – do not force it. Attempting removal with a slipping key deepens the damage and can lead to complete stripping of the socket. In such cases use a screw extractor, a drill to cut off the head, or – where access from the other side is possible – weld a nut to the shank. As a precaution: always use a hex key with a full profile and in good condition – a worn key damages the socket at normal torque.

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