FridgeFTA Free Blogs

There has been quite a bit of bashing of the SG6000 and hyping of the metal gear SG9120 by WSI and the few people that actually sell it. They claim this to be the “latest & most durable & heavy duty diseqc motor on the market” and how it is so much better than the “plastic gear” motor. Let’s take a look with pictures and some common sense.

One thing is immediately clear from the picture: The WSI SG9120 is a clone of the DMS SG6000. As is the norm, the DMS SG6000 was released first in early 2008. Source: DMS. WSI followed in October 2009 with the SG9120. Source: WSI/Galaxy Marketing product release posted on a pirate site by Galaxy Marketing. (Side note, Galaxy Marketing is the retail front name for WSI, it is WSI.)

Look at the control board. Relays, ribbon cable and other components appear to be exact copies. Same with the motor, gearbox and housing. The only change in the copy is the use of a Chinese iron or steel gear in place of the HD nylon DMS SG6000 gear. An interesting note about the gear design differences is that the metal gear has no stops. It has teeth all the way around, meaning it is possible to rotate the shaft 360 degrees. This means dish into ground, mast, supports, house, roof, or anything else in the way. The DMS SG6000 gear is only toothed in the areas of travel for the motor. If you get to the end you hit the solid part, shaft and dish stop moving and do not rotate into nearby objects.

WSI claims that the SG6000 gear is “plastic”. This is not true. It is a high tech nylon. Anyone that knows anything about synthetic materials such as nylon can see the advantages. Certain synthetics such as this nylon can be as tough as steel but do not shave off like you see with metal on metal gears. They are much more resistant to sudden start-stop or wind load shock. Nylon typically won’t snap when put under sudden force, where steel on steel will snap. The nylon gear produces much less friction and does not require a thick and heavy bearing type grease as is needed with metal gears. Anyone that lives in northern climates knows how heavy fluids and grease thicken and harden in cold. Bearing grease is thick enough at room temperature. This becomes effectively a solid at cold temperatures and could cause the gears to stick and produces a heavy startup load, just like trying to turn over your car in -20F weather. This produces heavy wear. Wear on any geared system means backlash adjustment to close the tolerances. Metal gears especially do not like being “sloppy” and can bind or lose mesh if allowed to operate that way. Another thing: metal on metal gears produce a byproduct: metal shavings. Metal shavings in any moving system drastically increase wear.

Another scientific fact about iron or steel: rust. Get water or even condensation in the system and eventually rust will form. Rust produces heavy weardown of metal components and of course more friction leading to more wear.

Enough about basic mechanics of geared systems. Let’s look more at the DMS SG6000 and the WSI SG9120. As you can see below, the housings are identical. Look at the curves and lines. Appearance and size wise it’s a clone on the outside too.

Finally, look at the bracket. It’s a copy of the duel elevation bracket DMS uses on the SG6000.

So it would appear that the “latest” motor is nothing more than yet another copy.

For another explanation of plastic vs steel gears please see here: http://www.dmsiusa.com/steelgears.html

Forum discussion: http://www.fridgefta.info/forums/showthread.php?tid=14450