OOSC, Part II, Item 2. Coupling Devices, b. Upper Coupler Assembly - Upper Coupler Bolts & TTMA Bulletin No. 110

The OOSC for upper coupler bolts and the interpretation in CFR 393.70 is outdated based on a new TTMA Bulletin No. 110. The number of bolts has been changed from the present OOSC. There is also criteria for trailers depending on the GVWR. The interpretation in the FMCSR is not reflective of what was currently in the OOSC. So both documents need to be updated.

Update the OOSC in relation to Upper Coupler Bolts to reflect the new information in the TTMA TB No. 110.

Amend the OOSC as follows:Section 2.b.(4)Any trailer with a bolted upper coupler, has fewer effective bolts than:Trailer has a G.V.W. of Maximum (68,000lbs): SAE J429 Grade 5 or ASTM A325 Type 1,2 and 3 Bolt- 6 per side, where the bolt size is 1/2" (12.7 mm).- 4 per side, where the bolt size is 5/8" (15.9 mm) or larger SAE J429 Grade 8 Bolt- 5 per side, where the bolt size is 1/2"; (12.7 mm).- 4 per side, where the bolt size is 5/8"; (15.9 mm) or larger Trailer has a G.V.W.R. of Maximum (85,000 lbs): SAE J429 Grade 5 or ASTM A325 Type 1,2 and 3 Bolt:- 8 per side, where the bolt size is 1/2" (12.7 mm).- 5 per side, where the bolt size is 5/8" (15.9 mm) or larger SAE J429 Grade 8 Bolt:- 7 per side, where the bolt size is 1/2"(12.7 mm).- 5 per side, where the bolt size is 5/8"(15.9 mm) or larger Trailer has a G.V.W.R. of Maximum (105,000 lbs): SAE J429 Grade 5 or ASTM A325 Type 1,2 and 3 Bolt- 10 per side, where the bolt size is 1/2"(12.7 mm).- 6 per side, where the bolt size is 5/8"(15.9 mm) or larger SAE J429 Grade 8 Bolt- 8 per side, where the bolt size is 1/2"(12.7 mm).- 5 per side, where the bolt size is 5/8"(15.9 mm) or larger Add the pictures of the bolts to the OOSC under this criteria for reference to determine the type of bolt to adequately apply the criteria. Petition FMCSA to amend the interpretation in 393.70 in regards to upper couplers to reflect this information.