M56 Nuts | McMaster-Carr

About 10% wider and taller than standard hex nuts, these nuts distribute the load over a large area. They're also known as heavy hex nuts. Grade 2H nuts are comparable in strength to Class 12.9 bolts. They're about 20% stronger than high-strength steel nuts and are used in heavy machinery, such as earth-moving equipment.

For technical drawings and 3-D models, click on a part number.

Thread
Size	Pitch, mm	Spacing	Wd., mm	Ht., mm	Specifications Met	Pkg. Qty.		Pkg.
Steel—Grade 2H
M56	5.5	Coarse	90	56	ASTM A194	1	000000000	000000

Metric Medium-Strength Steel Locknuts
for use with Cotter Pins—Class 8

Steel

Often referred to as castle nuts, secure these by inserting a cotter pin or safety wire through the slots and a drilled hole in your bolt for mild loosening resistance. They’re not recommended for use on parts exposed to high vibration because the pin is prone to shearing under prolonged stress. Height includes the slots. Cotter pins are not included.

Steel locknuts are best for dry environments, since moisture will cause them to rust. They are weldable and can be painted or finished.

For technical drawings and 3-D models, click on a part number.

Thread
Size	Pitch, mm	Wd., mm	Ht., mm	For Cotter Pin Dia., mm	Min. Slot Wd., mm	Min. Slot Dp., mm	Specifications Met	Pkg. Qty.		Pkg.
Steel—Class 8
M56	5.5	85	57	8	9	12	DIN 935	1	000000000	000000

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About Nuts, Materials, and Finishes

Metric Fine-Thread Medium-StrengthSteel Hex Nuts—Class 8

Metric Extreme-Strength SteelExtra-Wide Hex Nuts—Grade 2H

Metric Medium-Strength Steel Locknutsfor use with Cotter Pins—Class 8

Metric Fine-Thread Medium-Strength
Steel Hex Nuts—Class 8

Metric Extreme-Strength Steel
Extra-Wide Hex Nuts—Grade 2H

Metric Medium-Strength Steel Locknuts
for use with Cotter Pins—Class 8