Snap-on QJO36ARTH Open End Head, 1-1/8″ Thin Jaw for J-Shank (0.425″) Torque Wrenches

Description

Many motor bases slide on 3/4 in adjusting screws, and a jam nut holds each screw once the belt has its tension. A standard hex nut on that thread measures 1-1/8 in across flats. The Snap-on QJO36ARTH open end head grips it with a thin jaw on a J-shank (0.425 in) torque wrench. Its working limit is 60 ft-lb, which suits a locking nut rather than a structural joint.

Five facts on the 1-1/8 in QJO36ARTH

Thin or standard jaw at 1-1/8 in

Snap-on also makes the standard QJO36A at this size, with the same J shank and the same 60 ft-lb limit. So the thin jaw of the Snap-on QJO36ARTH open end head is the only real difference. It pays off where a second nut or a cast lug sits close behind the hex. For a higher spec, the standard heads climb instead: the QYO36A reaches 160 ft-lb on a Y shank, and the QXO36A reaches 240 ft-lb on an X shank. However, no thin Y head exists at 1-1/8 in. A tight, high-torque joint therefore needs a different head style, and Lost in HCM can suggest one.

Belt drives and the Snap-on QJO36ARTH open end head

After you set belt tension, the jam nut must hold the screw against vibration. Too little torque lets it creep back. Too much can stretch the screw or crack a cast base. A measured pull with the QJO36ARTH gives every motor on the line the same result. In addition, the slim jaw slips between the nut and the base lug, where a socket often has no room.

Pairing a J body with the Snap-on QJO36ARTH open end head

Choose a body whose range covers your value with room to spare. For example, the QC2I75 adjustable reads 5-75 ft-lb. The QD2IN100A dual-range body suits teams that work in N·m. Snap-on sizes its QD heads consistently from pin to fastener center, so no adjustment math is needed on that body. Whatever you choose, keep the setting at or under 60 ft-lb while this head is fitted. Its neighbors are the QJO34ARTH at 1-1/16 in and the QJO38ARTH at 1-3/16 in, so gauge the nut first.

Supply of the QJO36ARTH through Lost in HCM

SMK Vietnam shows this head as a partner listing, and Lost in HCM supplies it and prepares the price. Send your body model, the nut size and the torque value. Then request a quote from Lost in HCM for the 1-1/8 in thin head. You can compare other jaws in torque wrench heads and adaptors or contact SMK Vietnam for help.

QJO36ARTH fit and spec questions

What thread size goes with a 1-1/8 in nut?

ASME B18.2.2 sets 1-1/8 in across flats for a standard 3/4 in hex nut. The heavy hex nut for that thread is larger, so the QJO36ARTH will not fit it.

Can the QJO36ARTH work on a 29 mm nut?

No. Its jaw opens to about 28.58 mm, so a 29 mm nut will not enter, and a 28 mm nut sits loose.

Which 1-1/8 in head takes the most torque?

Snap-on’s standard QXO36A on an X shank, rated at 240 ft-lb.