TRUCK SERVICE MANUAL
MODEL NUMBER CONSTRUCTION
26DD SERIES EXTRA HEAVY DUTY P.T.O.
This is to advise of a modification precaution when installing or removing the lubrication valve adapter to provide
lubrication for PTO assemblies. Reports of lubrication valves missing on failed PTO equipped transmissions has
prompted the following recommendations.
It appears that customers are removing the lubrication valve adapter to facilitate drilling and tapping the cooler return oil
line fitting for providing lubrication to the PTO unit. During removal of this adapter, the lubrication valve can easily "pop out"
and be lost. Reassembly without the lubrication valve in place allows transmission lubrication oil to by-pass to sump thus
resulting in transmission failure.
As illustrated in Figure 1, it is permissible to provide PTO unit lubrication through a .032 orifice line from the cooler oil line.
However, it should be emphasized that drilling and tapping be accomplished without removing the lubrication valve adapter
from the transmission. If necessary to remove adapter, be sure a lube valve and spring are included on reassembly.