As far as I remember, the brake is on the motor shaft. When the DC motor is
energized, the shaft moves axially, pulling the brake disk away from the fixed
disk. As soon as the motor drive voltage is dropped, a spring moves the brake
disk back into engagement. It's not a HARD brake like a wedge, so it can be
defeated, but it's so far up the gear train that there's a lot of mechanical
advantage, and it doesn't take much braking action to be effective. A
disadvantage, of course, is that any mast torque is still applied to the entire
gear train. Because it's a "soft" brake, my G800SDX will move a bit in a hard
blow, but not much; and it can easily be reset to the desired azimuth. An
advantage of this scheme is that this relatively "soft" braking action reduces
any hard transient torque loads at the boom-to-mast interface; so that
minimizes the issue of bolt holes being wallowed out by repetitive hard stops
against a wedge. I suspect that's the reason Yaesu recommends pinning the
mast-to-rotator connection.
The G800SDX (and presumably the later models) has a ramp-up and ramp-down
action in the auto mode, and will coast a little in manual mode, before the
brake is applied. Mine has worked very well for many years with no maintenance
issues other than moist/conductive insect trash in the connector backshell
causing indicator problems. That was easily fixed with a cleaning and addition
of plain old Vaseline to fill the void around the electrical connections.
Chuck, N4NM
----- Original Message -----
From: Kelly Taylor
To: TowerTalk
Sent: Thursday, February 24, 2011 8:59 AM
Subject: [TowerTalk] Yaesu G800 rotators
Hi all,
I wonder if someone can answer this question, because the schematic and the
manual don¹t seem clear on the issue: is there a mechanical braking system
of some kind on the G800 or G1000 series of rotators?
If yes, is there a built-in gentle stop system like the brake delay mod for
the Ham-IV?
Thanks
Kelly
ve4xt
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