To paraphrase Vane Jones, "Knowledge is of little value until shared with others."

Sunday, May 6, 2012

AEFRE 49 #2B – Ordering the Power & Trail Trucks

Q-Car power and trail trucks were chosen because I knew the power truck would fit completely under the flat car portion of the locomotive. The exact dimensions of the Q-Car Low Profile power truck are shown below.

Here is part of the page from Q-Car’s web site describing the Low Profile power truck. A correction to dimension “C” needs to be made. The shortest wheel base this power truck can be made is 6’6” and not 6’. I had tried to get a 6’ Low Profile power truck made. It could not be done. This is the 3rdreason for picking a 6’6” wheel base side frame.
Q-Car Company Photo

Dimension “A” is the most important to building an under the deck power truck. This is the power truck I ordered. It has some important features to explain. The description of the power truck is: Power Truck w/Trailer Built Backwards with Flat Plate Bolster; Gear Ratio 24:1; Q-Car Type MT10LP; Motor Type Mashima 1628 Flat Can; Truck Type Kemtron Conversion; Wheelbase 78”; Wheel Diameter 33”

Built Backwards – The power truck is to be installed with the motor facing the end of the model. The gear box will face the center. This will provide clearance for the draft gear.

Flat Plate Bolster – A flat strip of brass will be mounted to the top of the power truck instead of the usual 2-56 screw with soft metal body bolster. The flat strip of brass is the body bolster. The screw holding the brass strip is soldered to the truck bolster. DO NOT ATTEMPT TO REMOVE THIS SCREW! 
Gear Ratio 24:1 – This is the slowest gear which can be mounted in this power truck.

MT10LP – This is a Low Profile design power truck.

Truck Type Kemtron Conversion – The old Kemtron, now PSC, sideframes were used to make the power truck.

Wheel Diameter 33” – The prototype had 33” wheels.

This is what the Q-Cars power truck looked like after I did some alterations. It came with the holes drilled and taped 1-72 in the “flat plate”body bolster. More on them later.

When I got my trucks the following alterations were made. The end pieces of brass were removed and replaced with 1/16” “L” shaped brass. I find these do not bend as easily as the flat piece of brass. Because of the“L” shape they are easy to install.

Before these end pieces were replaced the ends of side frames facing the ends of the model were shortened. There is just enough clearence for the flange on the wheels. This provided more clearance for the draft gear and the end foot boards on the model. File all joints smooth but do not remove all the solder.

Also notice the added small pieces of brass which help the change in side frames look more like the Peckham 30. A drop of solder helps to hold the added pieces in place. The brass side frame is more durable than the soft metal with pieces of styrene added.

If you carefully examine the photo of #49 you should notice something attached to the truck frames towards the inner part of the locomotive. I wanted to add more detail to my model. PSC #5342 Underbody Detail Kit was purchased. The #5345 Brake Hanger castings were added to the trucks. The balance of the castings in the Underbody Detail Kit will be used to finish the model.
PSC Catalogue Drawing

Here is a photo of the trail truck modifications and ready for installation. Note the modifications from left to right:
  • The end of the frame filed shorter with the "L" shaped piece of brass soldered on.
  • The addition of Q-Car CS 190 Dummy Traction Motor added for weight and to balance the weight of the powered truck.
  • A 0.005" think piece of brass shim. More on this later.
  • Another Dummy Motor Casting added for the same reason.
  • The PSC #5345 Brake Hanger casting.
  • The new journal lids can also be seen.

Finally, the power truck was tested. It looks like the red wire coming from the motor is the ground. There are small spaces in the truck bolster into which the wires can be woven. Do this so the wires do not have to be attached to the truck itself with thread.

The red wire was soldered to the cross frame piece for the ground. This soldering can be done with a 15 w iron.

A word of caution – no matter what the side frames are made of, dropping a power or trail truck does not help the geometry of the truck. Twisting the truck back into shape can help, but sometimes the truck has to be disassembled – parts unsoldered and screws loosened to get the truck level on the track.

When you get your power truck, open and inspect the gear box for grease. Adding rubbing compound and then allowing the truck to run for 1-2 hours will help to lap the gears. Of the total time, run the power truck in one direction ½ of the time and in the other direction the other ½ of the time. After doing this completely clean out the gear box with lacquer thinner and replace the grease with Labelle’s106 plastic compatible grease. Oil all points where the axle ends are in the side frames with plastic compatible oil.

Now we’re ready to build the flat car part of the model.


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