Wire Lockable Nuts | McMaster-Carr

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98 Products

Locknuts for use with Cotter Pins

Use these locknuts to secure rotating parts subjected to mild vibration, such as the wheels on carts and hand trucks. They’re not recommended for use on parts exposed to high vibration because the pin can shear under prolonged stress. These nuts are reusable, but you'll need a new cotter pin (not included) with each use.

Medium-Strength Steel

These Grade 5 or Class 8 nuts are your go-to for fastening most machinery and equipment. To avoid stripped threads during installation, make sure your screw has a comparable strength rating.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

Steel—Best for dry environments since moisture will cause these nuts to rust.

	Thread Size	Wd.	Ht.	Fastener Strength Grade/Class	For Cotter Pin Dia.	Specs. Met	Pkg. Qty.		Pkg.
Zinc-Plated Steel



		1/4"-20	7/16"	7/32"	SAE Grade 5	1/16"	—	25	000000000	000000


		1/4"-28	7/16"	7/32"	SAE Grade 5	1/16"	—	10	000000000	0000
		5/16"-18	1/2"	17/64"	SAE Grade 5	5/64"	—	25	000000000	00000
		3/8"-16	9/16"	21/64"	SAE Grade 5	7/64"	—	25	000000000	00000
		3/8"-24	9/16"	21/64"	SAE Grade 5	7/64"	—	10	000000000	00000
		7/16"-14	11/16"	3/8"	SAE Grade 5	7/64"	—	25	000000000	00000
		7/16"-20	11/16"	3/8"	SAE Grade 5	7/64"	—	10	000000000	0000
		1/2"-13	3/4"	7/16"	SAE Grade 5	7/64"	—	10	000000000	0000
		1/2"-20	3/4"	7/16"	SAE Grade 5	7/64"	—	10	000000000	00000
		9/16"-12	7/8"	31/64"	SAE Grade 5	9/64"	—	10	000000000	00000
		9/16"-18	7/8"	31/64"	SAE Grade 5	9/64"	—	10	000000000	00000


		5/8"-11	15/16"	35/64"	SAE Grade 5	5/32"	—	10	000000000	00000
		5/8"-18	15/16"	35/64"	SAE Grade 5	5/32"	—	10	000000000	00000
		3/4"-10	1 1/8"	41/64"	SAE Grade 5	5/32"	—	5	000000000	00000
		3/4"-16	1 1/8"	41/64"	SAE Grade 5	5/32"	—	5	000000000	00000
		7/8"-14	1 5/16"	49/64"	SAE Grade 5	3/16"	—	1	000000000	0000
		1"-8	1 1/2"	55/64"	SAE Grade 5	3/16"	—	1	000000000	0000
		1"-14	1 1/2"	55/64"	SAE Grade 5	3/16"	—	1	000000000	0000
		1 1/4"-7	1 7/8"	1 3/32"	SAE Grade 5	5/16"	—	1	000000000	0000
		1 1/4"-12	1 7/8"	1 3/32"	SAE Grade 5	5/16"	—	1	000000000	00000
		M6 × 1 mm	10 mm	7.5 mm	ISO Class 8	1.6 mm	DIN 935	5	000000000	0000


		M8 × 1.25 mm	13 mm	9.5 mm	ISO Class 8	2 mm	DIN 935	5	000000000	0000
		M10 × 1.5 mm	17 mm	12 mm	ISO Class 8	2.5 mm	DIN 935	5	000000000	0000
		M12 × 1.5 mm	19 mm	15 mm	ISO Class 8	3.2 mm	DIN 935	5	000000000	0000
		M12 × 1.75 mm	19 mm	15 mm	ISO Class 8	3.2 mm	DIN 935	5	000000000	0000
		M14 × 1.5 mm	22 mm	16 mm	ISO Class 8	3.2 mm	DIN 935	1	000000000	0000
		M14 × 2 mm	22 mm	16 mm	ISO Class 8	3.2 mm	DIN 935	1	000000000	0000
		M16 × 1.5 mm	24 mm	19 mm	ISO Class 8	4 mm	DIN 935	10	000000000	00000
		M16 × 2 mm	24 mm	19 mm	ISO Class 8	4 mm	DIN 935	5	000000000	0000
		M18 × 2.5 mm	27 mm	21 mm	ISO Class 8	4 mm	DIN 935	1	000000000	0000
		M20 × 2.5 mm	30 mm	22 mm	ISO Class 8	4 mm	DIN 935	5	000000000	00000


		M24 × 2 mm	36 mm	27 mm	ISO Class 8	5 mm	DIN 935	1	000000000	0000
		M24 × 3 mm	36 mm	27 mm	ISO Class 8	5 mm	DIN 935	1	000000000	0000
		M27 × 3 mm	41 mm	30 mm	ISO Class 8	5 mm	DIN 935	1	000000000	00000
		M30 × 3.5 mm	46 mm	33 mm	ISO Class 8	6.3 mm	DIN 935	1	000000000	00000


		Steel



				M12 × 1.5 mm	19 mm	15 mm	ISO Class 8	3.2 mm	DIN 935	10	000000000	0000


				M14 × 1.5 mm	22 mm	16 mm	ISO Class 8	3.2 mm	DIN 935	1	000000000	0000
				M14 × 2 mm	22 mm	16 mm	ISO Class 8	3.2 mm	DIN 935	1	000000000	0000
				M16 × 1.5 mm	24 mm	19 mm	ISO Class 8	4 mm	DIN 935	1	000000000	0000
				M16 × 2 mm	24 mm	19 mm	ISO Class 8	4 mm	DIN 935	1	000000000	0000
				M18 × 2.5 mm	27 mm	21 mm	ISO Class 8	4 mm	DIN 935	1	000000000	0000
				M20 × 2.5 mm	30 mm	22 mm	ISO Class 8	4 mm	DIN 935	1	000000000	0000
				M24 × 3 mm	36 mm	27 mm	ISO Class 8	5 mm	DIN 935	1	000000000	0000
				M30 × 3.5 mm	46 mm	33 mm	ISO Class 8	6.3 mm	DIN 935	1	000000000	00000
				M36 × 3 mm	55 mm	38 mm	ISO Class 8	6.3 mm	DIN 935	1	000000000	00000
M36 × 4 mm				55 mm	38 mm	ISO Class 8	6.3 mm	DIN 935	1	000000000	00000


M42 × 4.5 mm	65 mm			46 mm	ISO Class 8	8 mm	DIN 935	1	000000000	00000
M48 × 5 mm	75 mm			50 mm	ISO Class 8	8 mm	DIN 935	1	000000000	00000
M56 × 5.5 mm	85 mm			57 mm	ISO Class 8	8 mm	DIN 935	1	000000000	00000

Low-Strength Steel

Image of ProductInUse. Front orientation. Locknuts. Locknuts for use with Cotter Pins.

Image of Product. Front orientation. Locknuts. Locknuts for use with Cotter Pins.

Rated Grade 2, Class 6, or lower, these locknuts are about half as strong as medium-strength steel nuts. Use them with screws that have a similar strength rating to avoid stripping threads during installation.

Zinc-Plated Steel—A step up from plain steel, the zinc plating withstands occasional exposure to moisture.

Black-Oxide Steel—Typically chosen for their appearance, these nuts have a dark, matte coating to create a finished look. They offer minimal corrosion resistance, so they're best for dry environments.

Steel—Best for dry environments since moisture will cause these nuts to rust.

	Wd.	Ht.	For Cotter Pin Dia.	Pkg. Qty.		Pkg.
Zinc-Plated Steel



	1/4"-20	7/16"	7/32"	1/16"	50	000000000	000000


	1/4"-28	7/16"	7/32"	1/16"	50	000000000	00000
	5/16"-18	1/2"	17/64"	5/64"	25	000000000	0000
	5/16"-24	1/2"	17/64"	5/64"	25	000000000	0000
	3/8"-16	9/16"	21/64"	7/64"	25	000000000	00000
	3/8"-24	9/16"	21/64"	7/64"	25	000000000	00000
	7/16"-14	11/16"	3/8"	3/32"	25	000000000	00000
	7/16"-20	11/16"	3/8"	3/32"	25	000000000	00000
	1/2"-13	3/4"	7/16"	1/8"	25	000000000	00000
	1/2"-20	3/4"	7/16"	1/8"	25	000000000	00000
	9/16"-12	7/8"	31/64"	7/64"	10	000000000	00000


	9/16"-18	7/8"	31/64"	7/64"	5	000000000	0000
	5/8"-11	15/16"	35/64"	5/32"	10	000000000	0000
	5/8"-18	15/16"	35/64"	5/32"	10	000000000	0000
	3/4"-10	1 1/8"	21/32"	5/32"	10	000000000	00000
	3/4"-16	1 1/8"	21/32"	5/32"	10	000000000	00000
	7/8"-9	1 5/16"	3/4"	5/32"	5	000000000	00000
	7/8"-14	1 5/16"	3/4"	5/32"	5	000000000	0000
	1"-8	1 1/2"	55/64"	3/16"	5	000000000	00000
	1"-14	1 1/2"	55/64"	3/16"	5	000000000	00000
	1 1/4"-7	1 7/8"	1 3/32"	9/32"	1	000000000	0000


	1 1/4"-12	1 7/8"	1 1/16"	9/32"	1	000000000	0000
	1 1/2"-6	2 1/4"	1 5/16"	5/16"	1	000000000	00000
	1 1/2"-12	2 1/4"	1 5/16"	5/16"	1	000000000	00000
	1 3/4"-5	2 5/8"	1 1/2"	3/8"	1	000000000	00000
	1 3/4"-12	2 5/8"	1 1/2"	3/8"	1	000000000	00000
	2"-4 1/2	3"	1 23/32"	3/8"	1	000000000	00000
	2"-12	3"	1 23/32"	3/8"	1	000000000	00000


	Black-Oxide Steel



			1 1/2"-12	2 1/4"	1 9/32"	5/16"	1	000000000	00000


			Steel



					1/4"-20	7/16"	7/32"	1/16"	25	000000000	0000


					5/16"-24	1/2"	17/64"	5/64"	25	000000000	0000
					1"-14	1 1/2"	55/64"	3/16"	1	000000000	0000

Corrosion-Resistant Stainless Steel

18-8 Stainless Steel—The choice for wet and outdoor environments, these locknuts resist rust. However, they won't hold up to the harsh chemicals that 316 stainless steel can.

	Wd.	Ht.	For Cotter Pin Dia.	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	10-32	3/8"	1/4"	3/64"	5	000000000	00000


	1/4"-20	7/16"	9/32"	1/16"	5	000000000	0000
	1/4"-28	7/16"	9/32"	1/16"	5	000000000	0000
	5/16"-18	1/2"	21/64"	5/64"	5	000000000	00000
	5/16"-24	1/2"	21/64"	5/64"	5	000000000	00000
	3/8"-16	9/16"	13/32"	3/32"	1	000000000	0000
	3/8"-24	9/16"	13/32"	3/32"	1	000000000	0000
	1/2"-13	3/4"	9/16"	1/8"	1	000000000	0000
	1/2"-20	3/4"	9/16"	1/8"	1	000000000	0000
	5/8"-11	15/16"	23/32"	5/32"	1	000000000	0000
	5/8"-18	15/16"	23/32"	5/32"	1	000000000	0000


	3/4"-10	1 1/8"	13/16"	5/32"	1	000000000	0000
	3/4"-16	1 1/8"	13/16"	5/32"	1	000000000	0000
	7/8"-9	1 5/16"	29/32"	5/32"	1	000000000	00000
	1"-8	1 1/2"	1"	3/16"	1	000000000	00000
	1 1/4"-7	1 7/8"	1 1/4"	7/32"	1	000000000	00000
	1 1/2"-6	2 1/4"	1 1/2"	1/4"	1	000000000	00000