Description
A lock nut on a threaded rod poses a problem that no socket solves: the rod runs straight through it. The Snap-on QJO44ARTH open end head reaches that nut from the side. Its thin 1-3/8 in jaw mounts on a J-shank (0.425 in) body. In addition, Snap-on caps the head at 60 ft-lb, about 81.3 N·m.
What 1-3/8 in means on the QJO44ARTH
The partner title calls this a 1-3/8 in square drive head. In fact, 1-3/8 in is the jaw opening across the flats, roughly 34.93 mm. The QJO44ARTH has no square drive at all. Instead, the jaw itself bears on the nut, so it suits inch hardware only.
Tie rods and the Snap-on QJO44ARTH open end head
Machine frames and guard panels often brace with tie rods. A lock nut then holds each rod against a bracket or a turnbuckle. That nut usually sits hard against the next part, so a full-width jaw may not slip into the gap. The thin jaw of the Snap-on QJO44ARTH open end head fits there, and the J body clicks at your chosen value. However, a lock nut with a high torque spec may need a stronger head.
1-3/8 in jaws across four Snap-on heads
| Head | Jaw | Shank | Limit, ft-lb |
|---|---|---|---|
| QJO44ARTH | thin | J (0.425 in) | 60 |
| QJO44A | standard | J (0.425 in) | 60 |
| QYO44A | standard | Y (0.560 in) | 160 |
| QXO44A | standard | X (0.735 in) | 240 |
So the thin QJO44ARTH buys access rather than capacity. Where the jaw has room and the spec passes 60 ft-lb, move to the QYO44A or the QXO44A.
J bodies under the QJO44ARTH cap
The QC2I75 adjustable body reads 5-75 ft-lb, so hold its setting at 60 ft-lb or less. Likewise, the QC2P75 preset spans 5-75 ft-lb for repeat work on one value. For metric drawings, the QD2IN100A reads 20-100 N·m and also runs past 81.3 N·m. One CAT1500i footnote ties certain open end heads to the in-lb QC1P100 and QC1I200 bodies. Its text layer does not show which heads, so confirm your pairing with Lost in HCM.
Pull technique for the QJO44ARTH
Slide the jaw on until the nut bottoms in it, then keep the handle square to the rod. Pull slowly through the last few degrees, because a jerk can overshoot the click. Also free a rusted nut with a plain spanner first, as Snap-on advises against breaking fasteners loose with torque tools.
Supply of the Snap-on QJO44ARTH open end head via Lost in HCM
SMK Vietnam lists this head for its partner Lost in HCM, which handles supply and pricing. Share your J body model and the value on the drawing when you request a quote from Lost in HCM. Other jaws appear under torque wrench heads and adaptors, or you can contact SMK Vietnam.
Fit and range questions: QJO44ARTH
Does the QJO44ARTH accept sockets?
No. It grips the nut with an open jaw and has no square drive. For 3/8 in sockets on a J body, Snap-on lists the QJD12A-80 ratcheting head.
Is there a thin 1-3/8 in head for a Y body?
The CAT1500i thin table prints a QYO44ARTH row, yet it shows a J shank and 60 ft-lb. Because the data looks inconsistent, ask Lost in HCM to confirm it.
Which thin J jaws sit either side of 1-3/8 in?
The QJO40ARTH covers 1-1/4 in and the QJO48ARTH covers 1-1/2 in. Both carry the same 60 ft-lb limit.
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