A SERVICE OF

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7
Electrical 579 Family
Peterbilt Motors Company 7-15
TABLE 7-1. Truck Lift Axle Logic
Lift Axle Type
Raise Condition Logic
Lower Condition Logic
Steerable Lift Axle w/o Auto-Reverse
- Lift Switch is Inactive OR
- Park Brake Active OR
- Trans in Reverse
- Lift Switch is Active AND
- Park Brake Inactive AND
- Trans Not is Reverse
Steerable Lift Axle with Auto-Reverse
OR
Non-Steerable Lift Axle w/o Park Brake
- Lift Switch is Inactive OR
- Park Brake Active
- Lift Switch is Active AND
- Park Brake Inactive AND
Non-Steerable Lift Axle with Park Brake
- Lift Switch is Inactive AND
- Park Brake Inactive
- Lift Switch is Active OR
- Park Brake Active
Trailer Lift Axles
Trailer lift axles can be either EoA or Electric-Only type. There are a total of two available EoA trailer lift axle controls
using latching solenoids. If one axle is ordered, the customer will receive a switch labeled “Trailer Lift Axle”. If two axles
are ordered the customer can have a single switch that controls both axles or two switches. If two switches are present
they are labeled “Forward Trailer Lift Axle” and “Rear Trailer Lift Axle”.
FIGURE 7-21. EoA Trailer Lift Axles