Building the H.K. Porter 0-4-0T
by Harry Hungate
Updated: May 29, 2020
H.K. Porter Company 0-4-0T in 1/5 scale with full-scale young David.
This was Scott Thompson's idea: To build a pair of battery-powered steam look-alikes so that we would have something to play with while we were completing our live steam locomotives. His son's electric train provided the dimensions and Scott scaled the electric train dimensions up to approximately 1/5 full scale. The H.K. Porter Company built thousands of industrial locomotives in various gauges, and this small 0-4-0T engine is a fine example of which several original locomotives are still in operation. The suffix "T" means that the locomotive boiler is covered with a water tank. Coal is carried in a small bunker on the left side of the cab. Thus, no tender is required. Scott created an "ore car" to be attached to the locomotive. The "ore car" carries the battery box and electronic controls and provides a seat for the engineer.
Scott will have to tell his version of the story. Scott cut out the locomotive parts including the cab on the plasma cam at his factory, machined and welded the parts together and spray painted all of it gloss black.
My story begins when Scott delivered the partially completed locomotive to me, sans electric motor, drive train, driving wheels, connecting rods, etc. etc. I used one of the driver wheels from my steam locomotive to make a pattern for this locomotive. I created a wooden "doughnut" to fit around the driver to increase its diameter and Scott used this pattern to cast several other patterns in casting plastic. He took the patterns to the local foundry to have eight drivers poured in cast iron. His story is required here, as it is worth telling.
This is a totally "scratch-built" locomotive. There are no plans, prints, instructions, whatever--everything was designed and built by Scott and myself. As with most prototypes occasional design problems were encountered. Although these were frustrating at times, both of us profited from developing the solutions in that we could apply the lessons learned to the construction of our steam locomotives.
Motive power is provided by a re-purposed mobility scooter motor which we purchased from Craig's list: six motors for $50.00. This small 24 Vdc motor incorporates a gear reduction box which makes it ideally suited for this application. The chain drive sprockets and chain are from a junk bicycle. (Do you get the feeling that we are aiming for minimum investment?)
The drive train. (April 2020 update: The drive train is being rebuilt with #40 roller chain and sprockets as the bicycle chain and sprockets have proved to be too light and wore quickly.)
While Scott was machining the rough driver castings into finished driver wheels, I was busy fabricating the connecting rods and chain drive sprocket adapters, eccentric for valve gear, crank pins, running boards, front and rear buffer beams, coupler pockets, and cab.
Connecting rod with bronze bushing and oil cup.
The cab is a story in itself: Scott fabricated the sheet steel cab on the plasma-cam at his factory, tack-welded the front, sides and bottom together and primed and painted it gloss black. It looked too modern to me, so I spent a few weeks sawing up white oak drawer fronts which I salvaged from our kitchen remodeling project, and fastened each small piece of oak to the metal cab with contact cement and small bolts, typically 5-40 size. I used photographs of original Porters as a general guide. The activity was more like doll-house building than locomotive fabrication, but the final results were quite pleasing (and I can still count to ten!)
Scott created forming dies and formed/forged the number plate "1" for the front of the smoke box, just as would be found on the full size locomotive. My wife, Jane, painted the background bright red to provide contrast.
The axles ride in ball bearings fitted into the journal boxes. The journal boxes are milled wider at top and bottom to allow the wheels and axles to lift independently when traversing rough track. Coil springs above the journal boxes provide adequate suspension.
As soon as Scott delivered the four machined driver wheels, I was ready to quarter them and set the wheel gauge. A steam locomotive usually has two cylinders (rarely more). Unlike an automobile engine which develops its power only on one side of each piston, the steam engine is "double-acting", that is, steam is alternately applied to each side of the piston. To insure that the locomotive is always "self-starting" (both pistons are never on dead-centers simultaneously), one side is always offset ninety degrees from the other side. A quartering jig was used to determine the exact position for each pair of drivers. The driver wheels and axles were drilled and tapped to insert a set screw to lock the wheel to the axle, yet be able to dismantle the driver wheels from the axles when required. This technique is variously referred to as a "Scotch key" or "Dutch key" or whatever. When done accurately it serves the purpose very well. Loctite adhesive was also used to secure the drivers to the axles.
The front and rear buffer beams (bumpers in automobile-speak) were formed from hard maple. Typically, industrial locomotives are not fitted with "pilots" (or "cow-catchers"), but have steps front and rear for the convenience of the switch and brakemen who couple and uncouple the cars. The front coupler pocket and coupler are Allen Models castings. I turned the coupler pin from a scrap piece of C-1018 cold rolled steel. It has a pivot pin keeper to "keep" it in place. The running boards are pieces of white oak to match the cab.
The rear coupler pocket was made from pieces of C channel steel silver soldered together. It is interchangable with couplers or drawbars depending on what rolling stock will be attached to the locomotive.
Handrails were fabricated from scrap pieces of brass round bar and rod.
The boiler backhead and steam dome was designed and fabricated by Scott Thompson and is a work of art. I recently added three try cocks and a water gauge glass. Scott had already provided the holes for them. A brake lever is the latest addition.
I turned a dummy whistle and dummy safety relief valve from brass and copper scraps. These were installed on the steam dome and protrude through the cab roof as in the prototype locomotive.
The whistle valve contains a tiny normally-open pushbutton switch. When the whistle cord is pulled the switch closes and triggers a single chip recorder and ampifier to produce a recording of a steam whistle from a full size Porter 0-4-0T locomotive.
A second single chip recorder and ampifier produces the "chuff chuff" sounds of the steam exhausting up the smoke stack. Two magnets on the drive sprocket close a reed switch which triggers the recorder.
These electronics are hidden in the "boiler" shell, with power provided from the locomotive power pack.
The coal bunker for the locomotive is on the left side of the cab. A dummy store of coal was made from activated charcoal mixed with Titebond III glue. The top is hinged to provide storage space for small parts, tools, whistle, etc.
A matching bunker is on the right side of the cab and contains the power cable connectors.
With the locomotive nearing completion I set about designing the Power Pack. The 24V dc drive motor requires two 12 V dc sealed lead acid storage batteries for power. The Power pack comprises the battery box, battery charger, switches, circuit breakers, the speed controller for the motor and "throttle" and "reversing gear". A later addition was a small 12 V dc vacuum pump to operate the vacuum brakes on my D&RGW 6000 Series flat car which occasionally serves as the engineer's car.
The Power pack is a shell of 1/2 inch plywood with external beams to make it look like a coal bunker. I mixed activated carbon of the type used in aquariums with Titebond III glue and spread about 1/2" layer on the lid of the Power pack. When the glue dried the result looks like a bunker full of coal. A removable seat for the "engineer" fits over the coal bunker.
Sheet steel cab being overlaid with white oak planking.
Planking nearing completion. Plexiglas windows for safety.
Fixed windows on sides and opening windows on front.
Completed cab finished in honey oak stain and clear satin polyurethane.
Journal boxes modified for independent lift.
Number plate with red background.
Axle and driver drilled and tapped for the Dutch key. Hole for crankpin at upper right.
:The drivers were also drilled for the crankpins prior to quartering. With the wheel sets complete (drivers with crankpins, driven sprocket, journal boxes and bearings, springs, and eccentric for valve motion) they were assembled into the locomotive frame. The side rods were added and the main rods last. The crossheads were hitting the drivers on the back stroke, so some adjustments were needed on the width of the drivers. Off everything came and 1/16 inch of cast iron was machined off of the face of each driver. (Notation made for the fabrication of Porter #2!)
The 24 volt DC mobility scooter motor was installed and the drive chain and sprockets were installed. The chain and sprockets were salvaged from a scrap bicycle. These proved to be troublesome, with the chain jumping off occasionally and severe wear on the sprockets. After over a year in service the locomotive was returned to the shop (my garage) in April 2020 where it was fitted with #40 industrial roller chain and sprockets. The original drive ratio was 1:1.67 which proved to be powerful, but a bit slow. The new ratio is 1:2 which will increase top speed to a fast walk. Our train club has a 5 mph maximum speed limit when carrying passengers, so high speed is certainly not desired, and besides, this is a work horse and not a race horse.
While the cab was being completed I set to work on the headlamp. Scott had very thoughtfully fabricated and installed the headlamp bracket on the front of the locomotive. Some wood and metal scraps and a reflector salvaged from an old flashlight made up the major pieces of the headlamp. A round piece of plexiglas provided the lens. Jane sacrificed one of her flickering LED candles for the "light bulb". The finished product looks like the original kerosene lamps of the period (down to the almost useless brightness of the lamp!).
Illuminated headlamp.
Left and right bunkers in the cab.
Scott's boiler backhead and steam dome with recently added water gauge and try cocks. The firebox door and latch actually work.
Completed power pack. The lid removes to provide access to the power switch. The crank on the side is the "throttle" to control locomotive speed. The power cable plugs into the locomotive. Not shown is the reversing lever on the far side.
The electronics consist of a simple voltage controller for speed control and a double pole double throw knife switch for direction control. These were ordered from the internet and, of course, came from China. The power cable to the locomotive has Anderson PowerPole connectors to provide 24V dc for the drive motor and 12V dc for the sound system and headlamp. The various wires and connectors were supplied from my extensive supply left over from our boating days. The batteries were the most expensive part of this project at less than $200.
Left side view showing reversing gear lever, various switches, wiring and both batteries.
Scott designed a four wheel "ore car" from dimensions obtained from his son's model 0-4-0. He built it complete with four wheel brakes. This car carries the Power pack and tool box and provides a seat for the engineer.
Jumping forward to May 2020: the locomotive has been in service at Northeast Florida Railroad as the "yard goat", hauling carloads of crushed granite ballast and track laying materials since December 2018. Problems with the drive chain jumping off prompted me to bring it home for repairs. The bicycle chain and sprockets were badly worn, so I ordered #40 industrial roller chain and sprockets from McMaster-Carr. I reviewed the drive train ratio and decided to change the original ratio of 1.67 to 1 to 2 to 1. The 24V dc motor has power to spare and the extra 1.5 mph provided by the new drive ratio will not exceed 6 mph top speed. Scott Thompson to the rescue (again), as the new drive sprocket needed to be bored to fit the gearbox shaft and keyway cut in it. He also turned down the sprocket collar to 2.75" to fit the brake band that I purchased from ebay. Also, he milled a keyway on the driven axle for the new driven sprocket.
New drive sprocket prior to machining and after machining with key and keyway, brake band and cable.
Work continues on the brake mechanism. A cable support and guide fits against the inside of the boiler backhead to withstand the tension on the brake cable applied with the brake lever. The brake lever was turned and silver-soldered from C-1018 cold rolled steel. The pivot pin allows the lever to be quickly removed so the backhead will slide aft to gain access to the brake band and chain drive. Details, details,.....
On the left the vernier height gauge is used to lay out the cut lines on the brake lever pivot. On the right the completed pivot and lever are being silver soldered.
Completed brake lever installed on boiler backhead.
Upgrading the chain drive to #40 industrial roller chain will no doubt improve the reliability of this little locomotive, and in hindsight, I should not have relied on used bicycle parts. Lesson learned: do it right the first time. It's been a lot of work for me and for Scott, but for less than $100 in parts and countless hours of labor we will have an industrial quality chain drive system.
A chain breaker was ordered from Amazon and as I misplaced the half link to join the chain, another half link was ordered from Amazon.
It's now May 22, 2020 and the Porter is ready for the rails again. New chain drive, brakes, sound system, and full tear down, cleaning and lubrication. All dressed up and nowhere to gol
A short video of the Porter, Power Pack on ore car and D&RGW wooden flat car in operation.
Jim and Harry prepare the Porter for a work detail.