The tractor was needed to tow heavy artillery, but it could handle much heftier weights.
And now for an amusing episode from the vehicle's development process.
"On the issue of testing AT-45 tractors at factory #75
According to GOKO decree #5122ss from February 6th, factory #75 produced an experimental batch of AT-45 tractors (six instead of ten, as the factory was missing four engines). Factory #75 director Barykov is using the vehicles in an improper manner. Instead of performing trials, he is using them for various factory tasks, ie transport of various goods, using only the tractor without a trailer. This use is deemed acceptable by the factory as a method of combining trials and useful transport work.
This kind of use makes it impossible to observe their work from the point of view of military acceptance testing and give an evaluation of reliability when working in conditions of the Red Army, as the schedule of use is erratic and does not correspond to any trials schedule.
Factory #75 intends to continue using these vehicles, and with this in mind, the director intentionally delays the signing of an agreement with Artkom."
The newly rebuilding factory was also tasked with the higher priority T-44, and it could not manage two new vehicles, so the AT-45 died an early death. Yuri Pasholok writes that seven were eventually built.
Here's another photograph of the tractor, including another rare vehicle.
It's towing a T-34 recovery vehicle! You don't see one of those every day. Here's another picture.