Sperry Gyrocompass Information request

[Bowdrie]

Popped up first thing.
https://www.aero-news.net/index.cfm?...F-60E4B7472400

Or, https://www.theautochannel.com/news/...12/145497.html

I wouldn't trust any 40-year-old grease.
That link I posted for Aero News says, "Technical specs, and a sample offer, are offered on the company's website."
Perhaps find an FBO and beg them for a few ounces.

[GordMay]

Evidently, “Andok(R) 260" long-life sodium/mineral grease has been discontinued, by ExxonMobil, as has Nye Lubricant's "Rheolube 374A".

Castrol [Bray Oil Co] “Braycote 3214" Synthetic Grease, might be a suitable substitute.
➥ https://www.appliedthermalfluids.com...-applications/

➥ https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/0C27B74FDE97A10F80257796002F8774/$File/Braycote%203214%20_USA,%20English_.pdf

See also:
➥ https://www.astbearings.com/bearing-lubrication.html

[thadwald]

I have some Klüber Isoflex NBU 15 high speed spindle grease on hand.

https://supplimax.eu/sites/default/files/documents/Technische%20fiches/KLUBER/ISOFLEX%20NBU%2015.pdf

[smac999]

Sr-130 looks exactly like the gyro all the seaspan tugs were still using 15 years ago. (Unless there are very similar looking ones). No idea if they still use them or if they had to replace with newer ones by now. Some might still use them. Bc ferries probably also used them. Because sperry had a service shop in Vancouver. 15 years ago they were still servicing this gyro. Seaspan ones were removed and serviced every few years. As they ran 24/7/365. X ~ 30 boats.

I’m Pretty sure they had 1-2 big external boxes as well. Probably for power.

[thadwald]

Originally Posted by smac999

I’m Pretty sure they had 1-2 big external boxes as well. Probably for power.

Yup. One box for power supply and another that housed repeater/transmitter electronics. I only got the repeater, which I don't need.

The Keiki manual refers to the power supply as a Static Inverter (as opposed to a rotating one, I suppose). It produces 400hz 3phase . The static inverter also includes a 24v DC power supply for powering the Azimuth motor servo system.

This power supply box did not come with my unit so I made do with a modern variable frequency drive. These will happily produce 400hz, at any voltage between about 70 and 230, and the small ones cost only $120 and run off 110vAC household supply. In addition to that, I used a 24v power supply for powering the servo.

Before I powered it up, I dismantled the entire thing and cleaned and re-lubed all the bearings. It was a good thing that I did. because the old grease looked kind of like yellowed cottage cheese. I used the Klüber isoflex NBU 15 high speed spindle grease in the rotor bearings, ISO VG-32 hydraulic oil on the sensitive element bearings, and standard grease on the two outer bearing sets.

I may still need to look into the servo amplifier board. Strictly speaking, it works, but with a bit too much tracking error, causing a jerky compass motion and a bit of "looseness" in the compass response. I suspect aged electrolytic capacitors.

Tracking is a bit sluggish compared to what the literature says... I'm wondering if the ballast oil is old and thick or something. But it does track and settle, albeit a bit off-track--I suspect because it needs to be balanced since I had it apart. After having it run for a day or so, I no longer wonder why there's no corrosion; on the water, they're on all the time and as 1980s tech, they get pretty warm.

[davenrino]

Originally Posted by Bowdrie

I can't help you in your quest, (sorry,) I just wanted to comment on what a remarkable device you've got.
I did some close examination on a Sperry Gyro, but it was a 1930s vintage.
Now, if I could get my hands on a Sperry Inertial Navigation system I could be enthralled for days on end.

I flew DC10s for 14 years until 9/11. We used inertial nav from the 70s until switched to GPS the last couple years. Inertial was only used enroute as they could drift up to 50 miles on a 10 hour flight. The inertial nav gyros were also the platform for the gyro based flight instruments.

[Cruiser2B]

Try Mackay Marine, they recondition compasses and adjust them as well

[colsum]

From memory the Sperry SR series gyro was a variant of the TKC ES series, the main difference being the transmission output to the repeaters. TKC used a synchro output whereas the Sperry used a step output.

The system usually consisted of three units a power supply to convert the ships mains to 24V DC, an inverter to produce the 400Hz supply for the gyro rotor and follow up and the actual sensitive element itself. The 400Hz produced was single phase and phase shifting components were used to produce the 3rd phase. There was not a lot of torque applied to the rotor so it was slow in starting up. As the speed increased the reactance changed so the phase shifting components had to be altered to provide the correct phase angle hence you had a "start" circuit and a "run" circuit.

Like all gyro compasses the enemy is friction in the gimbal system and different manufactures used different methods to reduce this friction. TKC suspended the rotor by wires through guide bearings so there was minimal friction around the vertical axis. All bearings used were of high quality using special oil or grease. The follow up system was equally important and had to be smooth and tightly coupled to the sensitive element.

Overhaul was every two years where the element was stripped down and usually all bearings replaced. On assembly usual balances and adjustments are carried out so that the gyro aligns with north +/- 1-2 degree with no variable error.

[thadwald]

I got the electronics all figured out. I also covered most of the high voltage points with kapton tape after I got tired of getting zapped by them. Here's a short time lapse showing how it seeks and settles on the meridian.

https://youtube.com/shorts/AAtQAcduM0w?feature=share

It still appears to be about 2 degrees off but it's good enough for my purposes.

Many thanks for all the helpful information.

[GordMay]

Originally Posted by thadwald

... I also covered most of the high voltage points with kapton tape after I got tired of getting zapped by them...

FWIW: Evidently*, “Kapton” [wire insulation] doesn’t age well.

* “Aircraft Wiring Degradation Study” ~ FAA (2008)
➥ https://www.tc.faa.gov/its/worldpac/techrpt/ar082.pdf

“... The results demonstrate that PI* and PV aircraft wires that are present in high-moisture areas will have a higher risk of aging or degradation. ...”

* Kapton tapes are made from polyimide film, with silicone adhesive.

See also:
➥ https://www.cruisersforum.com/forums...ml#post2521012
➥ https://www.cruisersforum.com/forums...ml#post2521912
➥ https://www.cruisersforum.com/forums...ml#post2521042
➥ https://www.cruisersforum.com/forums...ml#post3729537

[hjohnson]

In all honesty, I don’t know that you will get much useful out of it, other than a fascinating look at how the technology works. I work with navigation systems for deep sea ships, and the one that still has a mechanical gyro (Raytheon Std22) has to replace the actual gyro element on a regular basis due to wear (every 4-5 years I think).

On the Std 22, the gyro element is a ball floating neutrally buoyant in a fluid. It’s an old school spinning mass gyro, and you can definitely hear it more and more as the bearings age.

In my part of the industry, most have switched to FOG (Fiber Optic Gyros), LRG (Laser Ring Gyroscope) or HRG (Hemisphere Resonant Gyros). They require much less servicing and don’t wear out.

[Bowdrie]

Originally Posted by davenrino

I flew DC10s for 14 years until 9/11. We used inertial nav from the 70s until switched to GPS the last couple years. Inertial was only used enroute as they could drift up to 50 miles on a 10 hour flight. The inertial nav gyros were also the platform for the gyro based flight instruments.

Yep, imagine this on your boat.
I'm sure it would need very little maintenance in a salt water/air environment.

https://www.youtube.com/watch?v=G3PVcYvbNp4

[hjohnson]

Originally Posted by davenrino

I flew DC10s for 14 years until 9/11. We used inertial nav from the 70s until switched to GPS the last couple years. Inertial was only used enroute as they could drift up to 50 miles on a 10 hour flight. The inertial nav gyros were also the platform for the gyro based flight instruments.

A good unit in the modern era is good for 1 nautical mile over 72 hours.

It blows me away that SSBNs (boomers) can be submerged for several months and be able to accurately launch their loads if they were ordered to do so. I actually know some of the techniques they use for navigation, but it’s still magic.

[El Pinguino]

Originally Posted by GordMay

Have you tried looking under C-Plath, Litton, or Decca, as well as Sperry?

In 1962 C.Plath was acquired by Litton Industries. Sperry Marine was formed in 1997, with the combination of C.Plath, Decca Marine, and Sperry Marine. In 2001 Sperry Marine becomes part of the Northrop Grumman Corporation.

I don’t know if this will help:
SPERRY GYRO-COMPASS GYRO-PILOT MANUAL
➥ https://ed-thelen.org/SperryManual.html

That manual is for the Sperry Mk 14, lovely machine and still being fitted to newbuilds in the 1950s. I believe the Tardis was a close relative.
Easily maintained, it was the second mate's job to look after it.
The other one around at the time was the Arma-Brown - a fraction of the size.

Edit - it was not quite as big as standard issue washing machine ..

[barcoMeCasa]

Originally Posted by Bowdrie

Yep, imagine this on your boat.
I'm sure it would need very little maintenance in a salt water/air environment.

Wow!! I used to work a bit of work with gyro stabilised cameras which looked a bit like that way back in the day.

Now use one of these for the boat autopilot >
https://shop.pimoroni.com/products/i...27843993960531
Costs less than couple glasses of wine in an airport.



No idea what these figures mean or how they compare --

2 FEATURES
2.1 GYROSCOPE FEATURES
The triple-axis MEMS gyroscope in the ICM-20948 includes the following features:
• Digital-output X-, Y-, and Z-axis angular rate sensors (gyroscopes) with a user-programmable full-scale range
of ±250 dps, ±500 dps, ±1000 dps, and ±2000 dps, and integrated 16-bit ADCs
• User-selectable ODR; User-selectable low pass filters
• Self-test
2.2 ACCELEROMETER FEATURES
The triple-axis MEMS accelerometer in ICM-20948 includes the following features:
• Digital-output X-, Y-, and Z-axis accelerometer with a programmable full scale range of ±2g, ±4g, ±8g, and
±16g, and integrated 16-bit ADCs
• User-selectable ODR; User-selectable low pass filters
• Wake-on-motion interrupt for low power operation of applications processor
• Self-test
2.3 MAGNETOMETER FEATURES
The triple-axis MEMS magnetometer in ICM-20948 includes a wide range of features:
• 3-axis silicon monolithic Hall-effect magnetic sensor with magnetic concentrator
• Wide dynamic measurement range and high resolution with lower current consumption.
• Output data resolution of 16-bits
• Full scale measurement range is ±4900 µT
• Self-test function with internal magnetic source to confirm magnetic sensor operation on end products