A Standish man was seriously injured Friday afternoon when his motorcycle struck a tractor-trailer hauling an excavator.

The crash happened just before 4 p.m. Friday when the driver of a Harley Davidson attempted to pass the truck on the right as it was making a wide righthand turn from Chadbourne Road onto Middle Jam Road in Standish, the Cumberland County Sheriff’s Office said.

The motorcycle driven by 60-year-old Raymond Taylor of Standish collided with the truck and was crushed under the trailer. Taylor was not wearing a helmet and sustained significant injuries, police said. He was taken to Maine Medical Center.

The sheriff’s office said driver inattention, failure to maintain control of a motor vehicle and improper passing played a role in the crash. It does not appear that speed or alcohol were factors, the sheriff’s office said.

The truck involved in the crash is owned by Gorham Sand and Gravel and was driven by Robert Walker, 39, of Gorham.