One of the most popular and most produced winches available today is the Carco PTO winches for in the 50,000 to 60,000 standard line pull range. The Carco 70a (PA56) and Carco 50b (PA55) are both extremely popular. As a winch manufacture Carco Winch is moving towards all hydraulic winches promoting the increased control hydraculic winches offer. PTO models like the 70a and 50b have been on the chopping block pushing to be replaced by hydraulic winches, but the fact remains the no hydraulic winch can match the pulling power of a PTO winch. This is the reason I believe the PTO winch platform for carco's 70a and 50b has been in production for so long and hasn't been replaced by any other new winches.
There are only a limited number of changes related to these winches but the changes are significant. There was an update for the older manual control valve to a manual control valve that performed better, and starting around the time of the CAT D6M Carco introduced the electronic valve for better performance. These valve changes were significant, but they are really tied to the winch installation package. The major change internally on the winch was related to a large design change in the clutch and brake.
Winch Serial numbers starting with 0100513 and higher no longer use the "spline" brake and clutches. These have been replaced with the Slotted components shown in the video below. When ordering parts it is CRITICAL you check serial numbers to be sure you order the correct parts. If you do have the older style spline setup, it's smart to check to confirm it's still splined because many operators have updated their components to the newer style slotted.
NOTE: the serial number break can be deceiving, as the first 2 numbers of the serial number stand for the model year! Pay careful attention to the break and remember that the first 2 numbers in the serial number stand for the year made, and the rest of the serial number is the sequence made. This can be tricky if your winch was made in the 2000's. A winch made in 2002 will look like 0200123 and a winch made in 1997 would look like 9700123 which is a number after 0200123, but you need to understand that the first numbers are the model year. A winch made in the 90's will need the update. Give us a call if you have questions.