When it comes to aircraft pulleys, there are many different varities. However, understanding aircraft pulleys is a bit more streamlined. Military Specification pulleys (Mil-Spec) are all manufactured to MIL-DTL-7034. When selecting the proper Mil-Spec Pulley, there are four variations to consider: MIL-DTL-7034/1, MIL-DTL-7034/2, MIL-DTL-7034/3 & MIL-DTL-7034/4. All four callouts have unique features. These features include: outer diameter (OD), cable compatibility, allowable loads, and bore size. At eSheaves, we want to provide a blog that looks at the specific differences between the Mil-Spec Pulley choices to ensure they buy the suitable product for their aircraft cable system. Below are the key differences between the Mil-Spec Pulley categories.

MIL-DTL-7034/1 – Cross-Reference MS20219 (superseded AN219) is a pulley product used for secondary control in Aircraft. MIL-DTL-7034/1 pulleys:

• Have two options for bore diameter depending on OD, 0.250" or 0.625". A pulley's bore diameter is also known as the center hole or inside diameter
• Come in a range of OD's from 1.312" up to 2.625"
• Have an allowable load of 480 lbs
• Fit cables that are either 1/16" or 5/32"

MIL-DTL-7034/2 – Cross-Reference MS20220 (superseded AN220) are pulleys used for flight control in Aircraft. MIL-DTL-7034/2 pulley specs:

• All have a bore diameter of 0.3125"
• Vary in OD from 1.750" up to 5.500"
• Depending on the choice of OD, have an allowable load from 500 lbs (with 1.750" OD) to 2500 lbs (with 5.500" OD)
• Fit cables that are 1/8″, 5/32″, or 3/16″

MIL-DTL-7034/3 – Cross-Reference MS20221: are heavy-duty pulleys used for secondary control in Aircraft. MIL-DTL-7034/3 pulleys feature:

• Two options for bore diameter depending on OD, 0.3125" or 0.500"
• A range in OD from 2.625" to 5.625"
• Variations in allowable load. With the smallest OD, a MIL-DTL-7034/3 pulley allows 2500 lbs, and with the largest OD can hold 7000 lbs
• The ability to fit cable sizes 3/16", 7/32", or 1/4"

MIL-DTL-7034/4 – Cross-Reference MS24566 (superseded AN210B) are anti-friction bearing pulleys used for control In Aircraft. MIL-DTL-7034/4 pulleys have:

• Three options for bore diameter, 0.190", 0.250", or 0.375" all dependent on choice of OD.
• 6 different OD options ranging from 1.250" to 6.000"
• An allowable load up to 4000 lbs on the pulleys with the largest OD
• The capacity to fit 7 different cable sizes depending on the choice of OD. MIL-DTL-7034/4 pulleys fit 1/16", 3/32", 1/8", 5/32", 3/16", 7/32", and, 1/4" cables

Despite all Military Specification (Mil-Spec) pulleys being manufactured to MIL-DTL-7034, we've shown that there are four unique variations to consider when selecting the right product for your aircraft cable system. MIL-DTL-7034/1, MIL-DTL-7034/2, MIL-DTL-7034/3 & MIL-DTL-7034/4. Choosing a pulley for the proper OD, cable size, and loads is simplified by understanding the key differences between the four Mil-Spec Pulley categories. 

If you want to learn more about Mil-Spec Pulleys, visit our product page here. Alternatively, if you have any questions, we can help! Reach out to us by email through sales@esheaves.com, by phone at 800-321-5667 or by filling out a Quotation for our Military Specification Pulleys here.