Motor mounting can vary drastically dependent on the motor, the mounting surface and the position required. This may be as simple as fastening the motor directly to the surface or require fabrication of a special mounting bracket. Most motors have drilled and tapped holes, but not all and some are not conveniently located. Size and shape may not permit desired mounting or may require major surgery to frame or shell. Large round cans do not fit well between drivers on steamers nor side mounting rails on box shaped brass locos. Flat cans are better and rectangular cross section, open frame usually fit best. Flat bottoms may require idler gears to attain mesh. Adding flywheels increases the fit problem. Selection may be influenced by all these factors.
Caution: Check screw
sizes carefully to avoid stripping threads. Most imported motor use metric,
while domestic use ASAE threads. Lengths may be very critical and
shortening may be required. Determine very carefully that they can not
touch any moving parts of the armature. Windings and commutators can be
easily damaged, necessitating repair or replacement.
Although it is not recommended , removing metal from motor may ease fit. Used in power truck applications, where they must pivot, some open frame motors had side tapers at the magnet end. Remember the chips are probably magnetic and must be removed thoroughly or they might wind up in the armature. Magnet material may be very brittle and hard, requiring grinding. This applies to the pole pieces to a lesser extent. Excess heat build-up may demagnetize. Carefully consider flux path to preserve it.
To assure good conduction, all leads should be soldered and anchored in such a way as to prevent interference with brush movement.
Before starting any physical work, examine possible positions by hand placing motor on frame and covering with shell to check fit. Observe angles, shaft center distances and mounting possibilities including brackets, screws and interference. Consider coupling and gear mesh possibilities. Gear boxes, U-joints and splines may simplify a very difficult position problem. Where worms must be located on motor shaft, allowance for easy mesh adjustment should be included. Consider removal for maintenance, repair or replacement. Remember, shimming is far easier than removing metal, when adjusting distances. Then plan your attack. On kits or RTR locos, the designer has already done this. Use or modify what has been done, if possible.
Do not get too fancy, more often the simplest is best. Many exotic mounting schemes have been suggested over the years with wild claims. Those tested showed very little, if any, advantage. Cantilever , spring, shock, glued and other mounts may even worsen performance . With motor shaft mounted worms, rigidity is an absolute necessity to maintain gear mesh.
Before selecting a mount just to reduce noise, first find the source and try to reduce the level. Granted the shell and other parts can act as sound boards, but a noisy motor may still be noisy after damping type mounting. Tuning motor can reduce whine and vibration. Search for loose parts that may vibrate and augment sound. Sometimes sound may be an ally in detecting failures.
Some models have mounts cast into frames or sideframes. The latter are common on smaller brass imports. Modify and use these if possible.
Note: Adjust brightness and contrast for optimum viewing.
Sideframe mounts on old Famoco B-1 switcher.
Single opposite side bracket barely visible to left of magnet.
For motor shaft, mounted worms in steam locos and no gear box, the easiest mounts are usually with angled, open frame motors. Many of the larger steam loco kits in the 50's used a Pittman DC 71 including Mantua, Penn-Line and Varney. Pre bearingless, Tyco Pacifics and Mikados still had the DC 71 mount, cast into the frame. With the PM-1, the geared driver was moved forward an axle. To replace an under powered PM-1, cut a new gear slot, drill mounting holes and shim, if necessary. Even though the angled PM-1 was not very good, Mantua's mounting was ingenious. A slot permits sliding the motor forward or backward to adjust mesh. Similar results can be achieved with oversized clearance holes, with a little care in locating them.
Pittman (Bowser) provided a very simple zee bracket for rear support. To change tilt of motor, it can be bent or a new one made. By modifying mounting holes to permit fore and aft movement, tilt adjustments can be made. For small changes shim washers may be added easily at either end. Using the angled corner as a fulcrum, a wide range of tilt is available including flat. While they have a screw hole near each end, U shaped prongs may be used, particularly at the magnet screw end, to avoid removing nut completely. Although they are more difficult to make, wedges can be used. Mantua used cast ones in their retrofit kits to mount flat bottom motors at an angle.
Note: Adjust brightness and contrast for optimum viewing.
Zee bracket on DC-71. Raises lip on rear may be removed.
Particularly with larger sizes, it may be almost impossible to tilt enough to attain a mesh, due to lack of shell clearance. Some motors even have extended front bearing plates to agrevate the situation. The only way to go is down. Penn-Line provided a recess in the frame to accommodate the bulge on the DC-60, in order to permit flat mounting. If possible these may be milled or filed to lower motor. Some early brass locos used a U shaped bracket between the frame sides, which pivoted on screws. Part of the motor was between the frame sides.
Some older 50's brass imports had end mounting hole, side magnet motors, which were mounted with the shaft vertical through the floor. The worm on the shaft drove the axle gear directly. This was also done on power trucks. They were crude but inexpensive at a cost of less than $10. Rivarossi mounted their pseudo-cans in GG-1 power trucks and some versions of steam in a similar manor.
Since the vast majority were not designed for model use, can motors present their own problems, Mounting holes may be on the end, barrel or completely lacking. Side magnet open frame motors usually have end mounting holes. In almost all cases, brackets will have to be bought or made. Sufficiently thick (.032") brass or other, non-magnetic metal should be used to avoid flux path corruption and provide rigidity. Most are too long to permit vertical shaft mounting.
End mounting "L" brackets for cans are available from Precision Scale and others, but in many cases, new screw holes or enlarged bearing bell housing hole is needed, or complete brackets must be made. The angle may be set to any value to achieve the required tilt, by using various BENDING METHODS. The bell housing hole need not be a complete circle. Often a U shaped prong with U shaped screw holes is sufficient and desirable to eliminate screw removal.
Side mounting may be used for both can and open frame motors by bending an angle bracket from sheet stock. Oversized clearance holes can ease alignment.
Note: Adjust brightness and contrast for optimum viewing.
Open frame sidemount from old brass powertruck, showing bright bottom floor mount flange with screws.
Motors without mounting holes present a challenge. Including straps, clamps and gluing, many methods have been developed, but not all worked well. Again of prime consideration are easy alignment and removal for servicing. In their diesel frames Model Power (Roco) cast a saddle and used a plastic strap that held the motor down with some difficulty. Frontrange provided plastic brackets. Even nylon wire tie-wraps have been used successfully with care. Nearly everyone is familiar with Athearn's rubber mounts. br>
Cementing may be necessary, but not directly to the frame. A removable plate or bracket should be used. Silicone based caulks and sealers have been used with some success for can motors with u-joints. But for worms on motor shafts, a more rigid bonding with ACC is preferable on a reasonably large, flat surface area, . Plastuct ABS seems to work well and may reduce noise. One example is the MOUNTING PLATE used with NWSL square open frame motors.
MOTOR MOUNTING EXAMPLES
Ingenuity may yield the only solution. Through examination of examples, a novel idea may pop up.
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