TEBU, (Tractive Effort Booster Unit), #1600 at the Eugene Roundhouse. These uniquelocomotives were slave units and required a power supply from other locomotives. The SP could use1 GP-40 coupled to one end to power both sets of trucks on the TEBU, or 2 GP-40s coupled to both ends, each unitpowering 1 truck. Regular assignment for the TEBU sets was the Toledo Hauler. On occasion, the Cascade Line helpersets were all in operation, which required the use of the TEBU sets during the layover days in Eugene. This photo shows the group of cables required for slave operation. © Joel Ashcroft