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DDC - Digital Direct Couplers
How To Use It, How It Works, Installation, SW Kit Parts and more


How DDC Works

Normal uncoupling is done by opening the knuckle on both mating couplers. This is OK when you have control of both couplers, like over an uncouple magnet. The problem with a DCC controlled couplers is you only have control of one coupler. In order to get around this problem the Digital Direct Coupler (DDC) found another solution. If you drop the coupler below the mating coupler you have a way to uncouple by controlling only one of the two couplers.

Standard Kadee couplers are used and modified to allow them to move from the normal position and below the mating coupler. The coupler pockets are attached to a push rod and are free to move up and down. The top end of the push rod is connected to a bell crank that is operated by a micro motor. The motor is controlled by a COUPLER CONTROLLER BOARD that is connected to the decoder. Two separate function keys independently control the front and rear couplers.

The front coupler is held in the up position by the bell crank in an over-center position. A small amount of clearance is needed for the motor to flip to the down position.

The rear coupler is also attached to a push rod that is connected to a bell crank in the cab area. This bell crank has a screw and three nuts used as a counter balance to hold the coupler in the up position. When the motor moves the coupler down the counter weight moves to a position that holds the coupler down.

The uncouple action is a little like the way a steam engine works, only the opposite. The steam engine converts back and forth motion to rotation. The uncoupler converts rotation to up and down action.

How to use Digital Direct Couplers (DDC)

DCC Systems that have Function (2) as a momentary contact like Digitrax will require holding the function button to maintain the coupler in the down position. The decoder or the throttle can be re-mapped to eliminate this.

To remove shell, start from rear, use probe to deflect locking tabs located below forward axle of rear truck. Do the same to tabs located near forward axle of front truck. When shell separates from frame spread pilots to provide clearance for coupler boxes.

Follow the same procedure when replacing the shell. Make sure all four tabs are locked/engaged to frame as coupler performance may be degraded.

The front coupler is controlled by Function 1, F1.

F1=Off, front coupler is up.
F1=On, front coupler is down.

The rear coupler is controlled by Function 2, F2.

F2=Off, front coupler is up.
F2=On, front coupler is down.

Parts List (DDC) of the Retrofit Kit
for Life-Like Proto 2000 HO SW Series Switchers

Bell Crank Front
Bell Crank Rear
Coupler /Box Assy
Circuit Module, Coupler Controller
Motors, Actuator, Coupler
Motor Mount, Front
Motor Mount, Rear
Nuts, 2-56, Counterweight, Rear,
Push Rod, Front
Push Rod, Rear
Keepers, Push Rod
Screw, 2-56, Counterweight, Rear Bell Crank
Screw, 2M.04 Fixture, Coupler Box Mounting
Screw, Slide, Mounting, Coupler Box
Washers, Fiber, Fixture, Front
Four Pack Kadee #5 or #58 Couplers

DDC Assembly-Installation Instructions (Rev D)
Life Like Proto 2000, HO, SW Series Switchers: (DDC) Retrofit Kit

Life Like Proto 2000 HO SW Series Switchers (DDC) Retro-Fit Kit. You need the following items to start:
(A) This kit of parts, (B) an SW-8/9 Switcher and (C) the TTE-SW9/12 decoder.

Read through these instructions before starting the installation!

Frame Modification

1) Either use the certificate enclosed to get a frame professionally machined or you can do the work yourself.

2) First carefully disassemble the drive mechanism. The manual that came with the switcher is a help at this stage. The P2K mechanism comes factory lubricated with a thick grease, and this grease is a wonderful "magnet" for the metal dust. If you have a machined frame skip to step 6.


3) See drawing for frame details. Remove the shaded portions of the bare locomotive frame. A hand held m otor-tool with cutoff wheel will work . Allow the wheel to do the work. This helps possibility of a bent or broken frame. De-burr any sharp edges and rough surfaces.

4) Check the frame with a straight rule to be sure it has not been bent and is still flat.

5) Clean the frame with mild detergent and water and allow it to dry. Touch up with black paint.

6) Re-assemble the basic drive mechanism including the power trucks and motor to the modified frame. Install the DCC decoder board. The coupler controller is designed to work with the TTE SW9/12 HO Decoder available from Tony’s Train Exchange. Following the manufacturers directions for installation. DO NOT connect front truck pick-up wires any lights. You can program the address, following the manufacturers’ directions for 2 digit or 4 digit address modes. There are a couple more times you will be testing the switcher. Each time you should check for shorts on the program track At this point test run the chassis to make sure all is OK.

Coupler Controller Installation

1) The weight located in the front is replaced by the front coupler mechanism and the coupler control decoder. Install the FRONT MOTOR MOUNT to the fram e. It is held in place by 3 screws that attached the front weight to the frame. Install the screws until they are snug, but do not over-tighten them, as this could damage the front motor mount. (Refer to parts drawing.)

Coupler Control Board

TTE-SW8/9 Special Decoder

2) Attach wires from the Coupler Control Board to the Decoder Board. Solder them carefully with a small soldering iron.Use solder made for electronics. Be careful not to form any solder bridges to any other circuitry. Refer to wiring diagram in the photo and drawing document for connections to the decoder board.

3) "Run-in" the coupler motors before installing them. Connect each motor to a 1.5-volt battery and run for about 10 minutes. This will seat the brushes.

4) Insert the BLUE wire from one of the coupler control motors into J7 from the BOTTOM of the board to the TOP and solder in place from the top side of the board. Insert the RED wire from the motor from the TOP through to the BOTTOM of the board into J6 and solder in place from the bottom of the board. Be very careful not to pull on the wires,they are delicate and are easily damaged.

5) Snap the MOTOR attached to the COUPLER CONTROL BOARD to the FRONT MOTOR MOUNT with the shaft facing toward the FRONT of the chassis with the RED wire on TOP and the BLUE wire is at the BOTTOM.

6) Use 2 pieces of double-sided foam tape such as Scotch Heavy Duty Mounting Tape to mount the COUPLER CONTROL BOARD to the installed FRONT MOTOR MOUNT. When mounting the COUPLER CONTROL BOARD, insert it BETWEEN the RED and BLUE wire of the installed MOTOR. Make sure that the circuit card does not touches the frame. The front edge of the circuit card should be even with the front of the FRONT MOTOR MOUNT and each side edge is aligned with the side edges of the FRONT MOTOR MOUNT.

7) Slide the FRONT MOTOR back until the black insulator on the back of the MOTOR touches the COUPLER CONTROL BOARD. (Refer to the pictures). Add a little ACC or similar adhesive to lock the MOTOR into position.

Finish Ready to Test before the Body Shell is installed.

8) Install the BACK MOTOR MOUNT by clipping the slots in the side-walls over the fram e side rails. DO NOT glue it in place at this time.

9) Snap the other MOTOR into the BACK MOTOR MOUNT with the shaft to the left as viewed from the front (radiator) end of the chassis. The motor(shaft end) should be even with the edge of the BACK MOTOR MOUNT. Connect the motor wires with the RED motor wire the wire connected to J9 on the COUPLER CONTROL BOARD. Connect the BLUE WIRE to the wire connected to J8 on the COUPLER CONTROL BOARD. Use heat shrink tubing to insulate the connections.

10) Connect the wire from the RIGHT side of the FRONT truck to J12. Connect the wire from the LEFT side of the FRONT truck to J1. Hint: Run wire from the BOTTOM of the COUPLER CONTROL BOARD to the TOP. Solder the
wire on the top of the COUPLER CONTROL BOARD.

11) Use the diagram to connect each of the wires installed on the COUPLER CONTROL BOARD. Double check to
ensure that you have the COUPLER CONTROL BOARD and decoder properly wired. The DECODER has each terminal labeled with the designation of the associated terminal on the COUPLER CONTROL BOARD. Dress the wires as shown in the photo so the shell will fit properly. Note that the rear MOTOR wires run from the TOP of the COUPLER CONTROL BOARD underneath the DECODER to the motor. Wires run across the top of the DECODER must be below the level of the four diodes located near the connection to J3 for the shell to fit. You can use Kapton tape to hold the wires in place and to help insulate the electronics from potential shorts. This tape is Digikey part number 3M541334-ND.

12) Place the unit on your program ming track. Now set the following CV’s to the specified values:
CV33 = 1 CV34 = 1 CV35 = 4 CV36 = 2 CV120 = 0* CV121 = 0 CV122 = 0
* 172 if you want the headlight to dim in reverse

13) Place the unit on an active DCC main and select the address as programmed previously. Activate the headlight (F0)and the white LED headlight should come on.

14) Press function F1 and FRONT COUPLER MOTOR should run clockwise (viewed from the front) about 1 second. Press F1 again and the FRONT COUPLER MOTOR should run in the counter-clockwise about 1 second. Repeat using F2. for the REAR COUPLER MOTOR. It should run counterclockwise (viewed from the front of the shaft) for about 1 second. Press F2 again and the REAR COUPLER MOTOR should run clockwise for about 1 second

15) Operating each motor in each direction several times.

16) If any functions is not operating, go back and check your wiring and make sure that no coupler wires or COUPLER CONTROL BOARD components are touching the chassis and that all connections to the decoder are correct.

Wiring for uncoupler boards.

Preparing the Couplers

1) Follow standard Kadee instruction sheet, assemble the supplied KADEE (#5 or #58) COUPLER and BRONZE COUPLER CENTERING SPRING into the COUPLER POCKET, then install the COUPLER POCKET COVER. Make sure that the coupler is installed into the pocket right side up. When the coupler, spring, and cover are properly oriented, apply a sm all amount of liquid plastic cement to the split line between the coupler pocket and coupler pocket cover. Set this assembly aside and allow it to dry. Then use a 3/32" drill bit to clean out any burrs from the center hole on the coupler pocket.

2) Remove the lower end of the Trip Pin(BRAKE HOSE). We recommend using a side cutter, and clip the coupler actuator rod off flush with the bottom of the coupler knuckle.

3) Cut the coupler pocket as shown in the drawing. This is a top view of the coupler. Note that only one of the "ears" is removed. You can use the original switcher coupler pocket as a guide for pocket length.

4) Make a second coupler just like the one above aside for later use.

Front Coupler Installation

1) Slip the top end of the FRONT PUSH ROD through the larger of the two holes in the FRONT BELLCRANK, and press one PUSH ROD KEEPER over the top end of the front pushrod.(See hint at the end of this step) Check to see that the front pushrod rotates freely in the front bellcrank hole. If the front pushrod binds, move the pushrod keeper slightly away from the bellcrank.Put a VERY SMALL AMOUNT of ACC adhesive on the backside of the pushrod keeper to hold it in place on the pushrod. BE CAREFUL THAT YOU DON’T GLUE THE PUSHROD TO THE BELLCRANK! HINTS: One way to get the small KEEPER on the rod is to use a piece of softwood like pine. Put the KEEPER on the wood. Then line up the rod with the BELL CRANK on it with the KEEPER. Lightly tap the rod with a small hammer. You can use a toothpick to transfer a sm all amount of ACC to the KEEPER.

2) Slide the small hole of BELLCRANK over the end of the MOTOR shaft until the end of the shaft is even with the front wall of the bellcrank. DO NOT apply adhesive.

Tape to hold rod while ACC sets.

3) Slide the bottom end of the FRONT PUSHROD through the hole in the remaining "ear" of one of the couplers.

4) Temporarily mount the COUPLER POCKET using the supplied short M2 X 0.4 metric screw and three Kadee 0.015" washers (Kadee part #208) under the pocket. Adjust the COUPLER POCKET so that it is square to the chassis and gently tighten the screw. When correctly positioned, the COUPLER POCKET will be square to the chassis and spaced 0.045" below the coupler-m ounting surface.

5) Rotate the motor shaft and bellcrank fully counter-clockwise so that the FRONT BELLCRANK is resting against the motor mount vertical partition. Use a sm all screwdriver or other appropriate tool to firmly (but carefully) push the FRONT PUSHROD down so the FRONT BELLCRANK firmly against its stop and the FRONT PUSHROD at the LOWEST position in the BELLCRANK hole. Once you have the FRONT PUSHROD properly positioned, use a piece of masking tape to hold the PUSHROD in position aligned along the machined edges of the engine chassis (see photograph). It should be parallel to the front of the machined edge of the chassis and held firmly against the machined edge of the chassis. M ake sure the PUSHROD is holding the FRONT BELLCRANK firmly against the stop when you tape it into position and is inserted into the ear of the coupler pocket as far as the locked position of the FRONT BELLCRANK will allow. T urn the engine chassis upside down. Apply a small amount of ACC adhesive between the FRONT PUSHROD and the coupler pocket. Allow the adhesive to set, or use an accelerator. Once set, any excess FRONT PUSHROD extending below the COUPLER POCKET may be trimmed with a diagonal cutter. Use a Q-tip to clean any excess glue or accelerator.

6) When set remove the M2 X 0.4 metric screw, tape, and the washers. Clean any residual glue or accelerator from all surfaces and install the COUPLER POCKET SLIDE PIN. Check the clearance and alignment of the assembly by rotating the BELLCRANK and MOTOR shaft both clockwise and counterclockwise. Look for any binding of the mechanism. With the bellcrank rotated fully clockwise (as viewed from the shaft end of the m otor), the coupler will be lowered until the FRONT PUSHROD touches the top of the front truck. W ith the bellcrank rotated fully counterclockwise, the bellcrank will rest against the vertical partition on the FRONT MOTOR MOUNT. The coupler pocket will reach its maximum height when the bellcrank is in the vertical position, and will drop slightly when the bellcrank rests against the vertical partition. T his is necessary to allow the it to reach its over-center position, which locks the coupler pocket in the "up" (coupled) position when in use.

7) This installation results in the coupler slightly low in relation to a Kadee coupler height gauge. This is for clearance in the uncoupled position. UP travel is limited by the bottom of the frame, and DOWN travel is limited by the front truck. The 3 washers to set the coupler in the correct vertical position is good compromise between these two positions. If you want the coupler closer to the proper up position, try shimming with a two 0.015" washer or with a combination of Kadee 0.015" and Kadee 0.010" insulated washers (Kadee #209). If the coupler too high, it will not clear other cars in the uncouple position. See the pictures for the proper U P and DOWN coupler positions for the front coupler:

Coupler in the UP position.
Coupler in the DOWN position.
Use two layers of double-sided tape between the circuit board and
the frame. See green arrow. (Only one layer shown.)

8) If there is any binding or interference between the coupler mechanism and the locomotive frame, remove the mechanism and remove sm all amounts of material from the frame to rem ove the interference. Remember to thoroughly clean the frame after filing.

Back Coupler Installation

1) The second coupler built previously will now be installed.

2) Slip the top end of the BACK PUSH ROD through the medium size hole in the BACK BELLCRANK, and press one PUSHROD KEEPER over the top end of the back pushrod. Check to see that the back push rod rotates freely in the back bellcrank hole. If the back pushrod binds, move the pushrod keeper slightly away from the bellcrank. A very small amount of ACC adhesive on the backside of the pushrod keeper to hold it in place on the pushrod. Be careful, don’t glue the pushrod to the bellcrank!

3) Slip the #2-56 SCREW through the largest hole in the BACK BELLCRANK and attach it with the #2-56 NUT. Tighten the nut securely, but do not over-tighten. Orient one of the 6 flat faces of the first nut such that it is parallel to the longest straight dimension of the BACK BELLCRANK. Add two more #2-56 nuts (total 3) and position them such that their flat faces are parallel to the first nut installed. In this orientation, they may not be fully tightened. Apply a very small amount of ACC adhesive between each pair of nuts to secure them in place.

4) Slide the small hole of BACK BELLCRANK over the end of the MOTOR shaft until the end of the shaft is even with the front wall of the BELLCRANK. Do not apply adhesive.

5) Slide the bottom end of the FRONT PUSHROD through the hole in the "ear" of the COUPLER POCKET. Temporarily mount the coupler pocket to the frame using the supplied short M2 X 0.4 metric screw. Note that the rear coupler pocket is mounted directly to the frame WITHOUT the Kadee spacer washers. The coupler pocket should be square to the frame.

6) Make sure that the front face (shaft end) of the MOTOR is even with the edge of the BACK MOTOR MOUNT and add a little ACC to secure the MOTOR.

7) Position the BACK PUSHROD in the ear of the COUPLER POCKETso the TOP of the BACK PUSHROD is even with or SLIGHTLY below the TOP edge of the frame. Slide the BACK MOTOR MOUNT back and forth until the BACK BELLCRANK just touches the BACK MOTOR MOUNT. Check that the TOP of the BACK PUSHROD is even with the TOP edge of the frame. MAKE SURE IT IS NOT ABOVE THE TOP EDGE OF THE FRAME! When the BACK PUSHROD is properly positioned, ap ply a sm all amount of ACC adhesive between the BACK PUSHROD lower end and the coupler pocket. Allow the adhesive to set, or, use an accelerator.

8) When set glue on the coupler pocket is set, move the BACK MOTOR MOUNT back and forth until the BACK BELLCRANK just touches the BACK MOTOR MOUNT. Make sure the BACK MOTOR MOUNT is square to the frame and the coupler box is just touching the frame. When the BACK MOTOR MOUNT is correctly positioned, apply a small amount of ACC along the seam where the BACK MOTOR MOUNT joins the frame on each side.

9) Turn the unit upside down and adjust BACK BELLCRANK such that it is parallel to the surface that the unit rests on (see picture). If everything is properly installed, the finished unit should look like the picture.

Upside down while ACC sets on coupler ear.

10) Once the adhesive on the BACK MOTOR MOUNT is set, replace the M2 X 0.4 screw with the COUPLER POCKET SLIDE PIN and clean up any glue or accelerator residue. Check the clearance and alignment of the assembly by rotating the BELLCRANK and MOTOR shaft both clockwise and counterclockwise. Looking for any binding. With the bellcrank rotated fully counterclockwise (as viewed from the shaft end of the motor), the coupler will be lowered until the BACK PUSHROD touches the top of the rear truck. With the bellcrank rotated fully clockwise, the bellcrank will rest on the BACK MOTOR MOUNT and the COUPLER BOX will just touch the surface of the frame.

11) The pictures show the correct operation of the rear coupler.

12) It is recommended that all sliding surfaces (including where the PUSHRODS may touch the frame) be lubricated with a LIGHT dusting of Labelle #134 Teflon Lubricating Powder. DO NOT use any oil or grease as they can cause the couple to "stick" to the chassis in the UP position.

13) A picture in the other section shows a top down view of the completed assembly.

14) At this point, use a Kadee coupler gauge to measure the coupler height of the front and rear coupler in the UP position. The rear coupler should be correctly positioned, while the front coupler will be low. The front coupler must be set low due to the limited clearance in the front of the engine chassis. Check out operation and make sure that there is approximately 0.010" to 0.025" clearance to a mating coupler in the DOWN position. Couplers should engage in the UP position. If it is necessary to slightly reposition a coupler box, then a pair of pliers can be used to slightly adjust the bends in the PUSHRODS. If you prefer, you can use an ACC de-bonding agent to remove the coupler box from its PUSHROD. Then clear the center hole with a 3/32" drill bit and the hole in the coupler box ear with a #55 (0.052") drill. Repeat the mounting instructions for the coupler box and make sure that there is no tension in the PUSHROD when it is setup in the jig position. If you damage the couplers or glue them into their boxes while adjusting things, DO NOT PANIC! Replace one of the extra Kadee coupler and pocket.

15) Because of the limited range of motion in the front coupler, it must be correctly aligned to assure proper operation. Use a standard Kadee coupler height gauge. Make sure that when the coupler is in the DOWN position that the top of the engine coupler clears the bottom of the Kadee height gauge coupler. Any cars that are to be used with the front coupler must be shimmed so that the BOTTOM of the car coupler is even with the BOTTOM of the Kadee coupler height gauge. Also make sure that the coupler in the mating car does not move vertically when the engine coupler moves to uncouple. If it does, judicious use of shims in the coupler pocket may help. Each car manufacturer has a slightly different coupler pocket arrangement, so some experimentation may be needed.

16) Too much tension on the mating couplers may prevent the mechanism from operating. We find that on a 2.5 percent grade, the unit will operate with seven or eight cars on the downhill side (this is also approximately the point where wheel slip starts to be a problem). On level track, the number of cars is not an issue as long as there is not too much tension between mating couplers. If you have trouble uncoupling, moving the engine slightly in the and introduce slack in the train. Normally, this is not be necessary. It is important that the couplers on any rolling stock have their couplers at the correct height. If a problem occurs with a car, check the coupler position. You may notice the pushrods set on the locomotive’s trucks. This is ok, as the pushrods are isolated from the frame.

Coupler in the UP position.
Coupler in DOWN position.

Finish ready to test before the body shell is installed.

Locomotive Shell Modifications

1) Following the instructions for replacing the rear headlamp, which were supplied with your locom otive, carefully remove the cab from the rest of the shell. Use care to avoid damaging the handrails, which lead to the rear cab door, as well as the horn and other small, delicate details.

2) Remove the cab interior insert, the backup light housing (designated as part of #22 group in the operating instructions), and the backup light bulb. Also remove the backup light connection tabs and wires.

3) Remove the cab side window insert. Carefully remove the side windows form the plastic arch that joins them to each other. Glue the windows back into the cab openings using a SMALL amount of liquid plastic cem ent.

4) Use a sharp hobby knife to trim the portion of the walkway inside the cab to the interior width of the cab. See photo of modified and un-modified walkway. The upper shell is modified and the lower shell is the unmodified. Shown is the cab interior insert (on the lower, unmodified shell), as well as the backup light housing (the gray rectangular item in the cab of the upper shell) and the backup light leads with the connectors removed.

Lower shell is stock and the upper shell has the area below the cab cut out.
The light is still in the upper view, but must be removed. Area to be shaved
for PUSHROD clearance is shown in red.

5) Shave off some of the inter body shell to allow room for the front PUSHROD to clear the underside of the front walkway. See the last page of the photo drawings for location.

6) Re-install the cab to the rest of the body shell.

7) Note: The coupler slides up and down in slots that are in the front and rear pilots, between the pilot footboards. There are small bumps on each edge of these pilot slots that need to be removed so that the coupler pocket does not catch on it. Take a small file and file away the bump, and make sure that the vertical surfaces are straight and sm ooth.

8) Before installing the body shell check to be sure on wires will interfere with the uncouple mechanism when the shell is installed.

9) Re-install the shell onto the frame. Install the front (radiator end) of the shell first, sliding the front coupler and coupler pocket into the slot on the front pilot. Then, lower the back (cab end) of the shell onto the frame until the coupler pocket touches the back footboards. Gently spread the footboards apart just enough so that the coupler pocket slips down between them. Then continue installing the shell normally until the locking tabs engage into the slots on the frame. If you have any trouble with the front coupler, check the frame alignment. You may need to trim a bit of the footboard if the back coupler does not move freely.

10) CONGRATULATIONS! We realize that this has been a fairly complex modification. If you have made it successfully to this point, you are ready to start switching out cars to all of your industries!

The Front coupler is controlled by:
Function 1, F1
F1=Off Front coupler is up.
F1=On Front coupler is down.

The Rear coupler is controlled by:
Function 2, F2
F2=Off front coupler is up.
F2=On front coupler is down.

NOTE: If your cab/throttle is setup for F2 to op erate a whistle function the coupler will go down when press the key and up when released. One way to fix this is to change the function map the rear coupler to F3. Just program CV37=2. To remove F2 from still controlling the coupler program CV36=0.

The End of the Instructions and the Beginning of Fun Switching

21Oct03 DEF

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  Phone: 800-978-3472 or 802-878-5005.
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