Was removing a tractor from the trailer, while backing down the ramp, the welds on the ramp failed suddenly, causing the ramp to drop to the ground, while the tractor was still partly in the trailer. The impact caused the tractor windshield to shatter and cause minor injuries to the operator (cuts on exposed skin). Upon inspection, it was found that the welds for the ramp were inadequate in both quality and number. Most of the welds had insufficient penetration, and there was minimal stitch welds across the width of the frame. The weight of the tractor was approximately 2000lbs. There was no ramp load rating either posted on the trailer or in the literature provided. The salesman said it was around 2500lbs, and a call to the factory confirmed that. Standard engineering principles would expect to have a factor of safety of at least 1.5x rating to prevent failure at rated conditions. There should also be a load rating label to guide the consumer.