Pittman X-Motors
DC-65X and DC-85X
Pittman, like almost all slot car motor manufacturers in the early 1960s, designed and rated their motors in terms of the amount of direct current (DC) voltage they were intended to operate on. Since the "standard" DC voltage for model trains and slot cars (1/32 and 1/24 scales) is 12, Pittman wound their slot car and train motors to run on 12 volts DC.
Here are data sheets for the DC-65 and DC-85 dated March 1960. These are definitely 12 volt motors, although you might notice Pittman could and would also wind them (in production quantities on special order) for anything from 3 to 28 volts:
Given Pittman's emphasis on reliability, it is safe to say that a 12 volt Pittman motor would happily power your slot car around the 12 volt track all day long and never get so hot that something would fail. Competitive speed and stone-cold reliability; Pittman was happy.
This 12 volt motor stuff was all well and good until some clever racer came along with a motor wound for 6 volts and promptly blew your doors off. Pittman might have still been happy, but you're not. Now you need a "6 volt" motor to be competitive.
Even before the end of 1963, Pittman was not entirely unaware of this. Pittman realized they needed to "soup up" their product line.
Pittman improved and upgraded their motors in two different ways, and used different designators to indicate this. The first type of improvement or upgrade was mechanical, such as the materials used for motor parts (such as the end frames), or the configuration of the brush spring assembly, or the location of the brush plate on the motor frame.
These mechanical improvements and upgrades were indicated by a letter added to the existing motor part number, so a DC-65 became a DC-65A, or a DC-85 became a DC-85A. They were however still 12 volt motors.
The second type of upgrade was purely for performance, and it is arguable that the Pittman factory did not really consider this an "upgrade" so much as a slight change in the production order. They simply wound the armature for 6 volt operation instead of 12.
These upgrades were indicated by a dash number added to the existing motor part number, so a DC-65A wound for 6 volts became a DC-65A-6, and a DC-85A wound for 6 volts became a DC-85A-6.
The 1964 Auto World catalog reflected these two types of designators:
But Pittman also did something else late in 1963; they created an "X" designation variant for the DC-65 and DC-85.
The DC-85X is definitely a 6 volt motor, as you can see in the Pittman ad from the March 1964 issue of Car model magazine, shown below.
But Pittman does not actually say anything about the DC-65X anywhere I've been able to find.
However, Howie Ursaner writes: The dc65x motors were rated at 6v . The dc65 rated at 12v. The x was a much hotter wind. When I talked to Charlie Pittman (in 1963) I told him we needed hotter winds.
Also, the Car Model magazine article shown below indicates that both the DC-85X and the DC-65X were 6 volt motors. As you can see in the by-line, this article was written by Chuck Hamill, who was at the time a contributing technical editor to Car Model. Note in the topmost photograph both motors are marked "6V".
On the article's following page (not shown), in a photo caption Chuck indicates that the big difference in the X models is "the special windings on the armature which lower resistance and increase rpm" (emphasis added). Chuck does not however say what this big difference is in comparison to.
Confused yet? Consider this: The DC-85A-6 and DC-85X are both equipped with a 3/4" diameter 6 volt 5 slot (pole) armature with no timing or balancing, and both motors have a 13 lamination magnet field. There appears to be no mechanical or electrical difference.
Likewise the DC-65A-6 and DC-65X; they both have 17/32" diameter 6 volt 5 slot (pole) armatures with no timing or balancing, however, the DC-65A-6 has a magnet field consisting of 17 thin laminations, while the DC-65X has 14 thicker laminations, identical to the DC-65A. This appears to be the only difference.
Nevertheless, the only thing Pittman will ever say is "special windings".
