Saturday, 7 January 2012

Hydraulics vs. Electrics

Hydraulics vs. Electrics (Ramp)

While the ramps of the CH-113 and CH-113A were for a time functionally different, visually they were almost identical.  It is unlikely the average modeler will take the time to deal with the comparatively trivial differences. And in any event I do not have a lot of photographic support, but my memories and understanding are, I believe, still capable of addressing the subject with a high degree of accuracy. As major modification programs began, the differences were soon lost.

Labrador ramps were electrically operated whereas Voyageur ramps were hydraulically operated.  The Labrador ramp could be operated using switches located at the front of the cabin or at the left rear of the cabin, but slightly ahead of the engines.  There were also switches on the left side, and outside, of the tail below the aft pylon.   Once activated the ramp movement, up or down, was facilitated with screw jacks located one on either of the ramp a few inches aft of the ramp/fuselage hinge.  Essentially large worm gears, the screw jacks were dark gray, almost black, in colour.

Labrador ramp switches are visible in line with and almost half way between the hoist drum and hoist boom. This DND photo is part of my personal collection.
The gauges to the right of the FE compartment, and hydraulic hoist are telltale signs this picture is of a Voyageur. Sealing the deal is that the the FE with the glasses is Gary Bond, with whom I flew while we were part of 103RU (Gander). The circular opening directly above the gauges is where the Labrador hoist switches were located on Labradors. This DND photo is also part of my collection.
Another view of a Voyageur. Photographer unknown.

Voyageur ramp movement was initiated by two control levers, located below the engine compartment and aft of the ramp/fuselage hinge.  The same levers could be accessed from the inside or from the outside by reaching through a small hatch.  A pair of ramp actuators that were silver in colour facilitated movement of the ramp.  At some point late in the service life of the Labradors, probably SARCUP, hydraulics replaced some electrically operated functions such as the ramp and the internal back up hoist.

These DND photos that are part of my collection, show the access panel to the ramp controls on the port side of the aft fuselage of Voyageurs.

The crooked handle to the right of the seat is used to raise the lower ramp. To close the lower ramp, the ramp control was pushed forward and a crew member activated a hydraulic pump that raised the ramp. As long as you pumped the handle the ramp would go up. To close the aft upper hatch, one just put the aft upper hatch control in the opposite position and let gravity do its thing as the aft upper hatch fell  to close. Note as well the roller tracks on the ramp of the Voyageur. Photo - Scott Hemsley
The only other ramp difference was the existence of rollers on ramps of Voyageurs, a continuation of those on the fuselage floor, which will be discussed, in later paragraphs.  Rollers were an Army requirement not considered for Labradors. When Voyageurs were transferred to the Air Force for SAR duties, the rollers were at some point removed.  A lack of relevant photographs makes it difficult to narrow the period of their removal down.!

This picture taken by Jeff Wilson is of Labrador 301 in National Aviation Museum in Ottawa. Note that there are no roller tracks. Also of note are the two ramp extensions for loading/off loading equipment on/off the helicopter. The ramp extensions were used by both the Labrador and Voyageur.

SARCUP modified Voyageur - Photo Derek Heyes

Voyageur - note rollers removed from tracks.
This photo from the internet is of a H-46, but is similar to a Voyageur in couple of ways that if not already revealed, will be in other posts. Note that the shape of the ramp hydraulic pump handle is very much like that used on Voyageurs early in their service with Canada.
Note shape of ramp hydraulic pump handle on this aircraft.

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