Re: (ET) E-15 Reverse relay Arcing

[Chris Zach <czach computer org>]

The E15 is a bit different than the E20. On the E20, reverse was made by 
using 4 contactors to reverse the polarity on the armature. They were in 
a push-pull arrangement so a failure couldn't blow the armature sky 
high. As a result, in reverse the tractor had less torque (due to the 
fact that the field was weakened since technically it is a compound-ish 
motor)

On the E15, reverse is controlled by using a single relay to reverse 
polarity on the field. A lot cheaper, but if the tractor is moving 
forward *at all* when you toss it into reverse you are going to get a 
relay-melting spark.

There might be a varistor that goes across the relay to absorb the 
sparks, or a capacitor. If so I'd bet it's blown.

Chris


Steve Caplan wrote:

> Hi group,
>         My E15 reverse relay arcs alot. I have burnt up two relays. They 
> were both used. Is this because they were old and probably not adjusted 
> properly or is there some other cause I should look for?  Can I expect it 
> to work if I order new relays from Bill? Can I expect to find them at a 
> local large electronics supply house?
>                                                         Thanks in advance 
> for your help,
>                                                         Steve
>                                                         Baltimore County, 
> Maryland