What You're Looking At
This is a trailer air brake S-cam, right-hand rotation, 28.19 inches long, 10 spline on the actuator end. It's the shaft the brake chamber pushrod turns to spread the shoes against the drum. Meritor spec, common on a lot of van and flatbed trailers running Meritor Q-Plus or similar foundation brakes.
Length and spline count matter more than the brand name stamped on it. 28.19" is measured tip to tip, and 10 spline has to match your slack adjuster - not 24, not 28. Get either wrong and the cam either won't seat or you'll be over-torquing a slack adjuster that's fighting geometry it wasn't built for.
RH means the direction the cam rotates when the brakes apply, viewed from the brake chamber side. Mix up left and right and the brake either won't release fully or drags - either way you're back under the trailer in a week.
Why These Numbers Cross
R607317, CS41539, 41539, 2210-C-7621, 17-640, and 124.102316.02 all show up because different manufacturers and axle builders (Meritor itself, plus aftermarket cam suppliers) have stamped this same length/spline/rotation combo under their own part numbering over the years. Same physical cam, different catalog trail.
Where this bites people: bushing wear changes how the cam feels going in, but it doesn't change the spec. If your old cam is grooved or the bushings are shot, that's a wear issue, not a sign you need a different cam. Check the actual stamped number on the old shaft, or measure spline count and overall length yourself if the stamp's worn off.
Drum size and slack adjuster arm length aren't part of this cam's spec, but they live on the same axle, so don't assume a cross-reference here means your slack adjuster or drum is covered too. This part number is for the camshaft only - check those separately if you're replacing more than one component.
Ordering It
Confirm by the number stamped on your old cam or by VIN if you're not sure which axle spec you're running - S-cams get swapped in fleet shops and paperwork doesn't always follow the parts.
$41.99, aftermarket, 6+ month warranty. We keep these in stock in Tacoma for same-day pickup or counter pull, and we ship nationwide if you're not local - trailer parts move fast enough that we don't sit on axle-spec items.
E11866 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to E11866. Use them to identify the part — then confirm the exact fit by VIN or the number stamped on your old unit before you order. An interchange is a starting point, not a fitment guarantee.
| Brand / Line | Cross-Reference Numbers |
|---|---|
| OE/Cross-Ref | R607317, 2210-C-7621, CS41539, 41539, 17-640, 124.102316.02 |
Frequently asked questions
Does E11866 fit my Wabash trailer?
Depends on the axle, not the trailer brand. Wabash trailers run different axle suppliers depending on model year and spec order. Check the stamp on your old S-cam or measure spline count and length - if it's 28.19" RH with 10 spline, this crosses. If you're not sure, give us the VIN and we'll pull the axle spec.
Is this the same as the Meritor CS41539?
Same physical spec - length, spline, rotation - just a different catalog number from a different point in Meritor's own numbering history. This aftermarket E11866 is built to that same 28.19" 10-spline RH spec, not a Meritor branded part, but it interchanges with CS41539 based on physical fitment.
How do I know if I need RH or LH?
Stand at the back of the trailer facing the axle - if the brake chamber and slack adjuster are on the passenger side of that axle end, you're usually looking at RH, but the real answer is checking rotation direction on the old cam or matching the stamped number. Don't guess on this one, wrong rotation binds the brake.
Not sure it fits? We check before you pay.
Run your VIN and we’ll match parts to your exact truck, or call the counter — a person who knows trucks verifies fitment by OEM number before the order ships. No wrong-box returns.
More cross-reference guides
Need the part, not just the reading?
Every part below is a Premium Quality aftermarket Direct Replacement with published OEM cross-reference numbers, a 6+ month warranty and same-business-day shipping from Tacoma, WA. Not sure it fits? Run your VIN — or call and a person who knows trucks will verify fitment before you pay.