The New Zealand Railways Magazine, Volume 3, Issue 1 (May 1, 1928)
The “Stirk” Hiloplane Machine
An outstanding feature of the new machinery programme in connection with the reorganisation of our workshops is the importation for Hillside of one of the hiloplanes manufactured by Messrs. John Stirk and Sons, Halifax, England.
In my opinion, the merits of these machines do not belie the claims made for them by the manufacturers.
The Stirk hiloplane embodies a patent split field drive which provides for any range of cutting and return table speeds. The outstanding advantage of this feature is that the cutting speed is entirely independent of the return speed, the speeds being controlled by wheels on the control panel.
An accellerating device is fitted for the purpose of speeding up the table between two cuts, thus reducing time to a minimum. This device is controlled from the panel and any desired acceleration can be obtained.
The Stirk patent electric rotary feed is a most important feature of the machine, and is far ahead of anything I have seen in this respect. The feed is controlled by a motor which is wound to give a half or full turn of its shaft. This shaft operates on a gear-box which drives the power traverse shaft operating the cross-slide and horizontal and vertical tool rests.
An accurate feed of 1/32 to 1/4 of an inch, also broad feeds ranging from 1/2in. to lin., can be obtained, and these feeds are regulated by simple levers at the gear-box. A special feature of the gear-box is that double of the above feeds can be obtained by simply reversing a tumbler switch.
Another switch of the tumbler type operates on a solenoid, which lifts the tool-box on the return stroke of the table, thus eliminating the dragging of the tool over the work, and at the same time saving much of the wear on the keen edge of the tools.
The two tool heads can be worked together, or independently—up, down, in, or out. The two side heads work similarly. All of the operations, including the raising or lowering of the cross-slide, can be carried out entirely at the will of the operator, each and every movement being controlled, when necessary, by means of an inching button. Another important feature of the machine is that all slide travels are equipped with safety stops, which cut off the current when the end of the travel is attained, thus effectually protecting the operator or the machine from any injury.
The current is supplied by an A.C. motor generating set which supplies direct current to the main and supplementary motors.
A good idea of the scope and capabilities of the Stirk hiloplane machine is conveyed by illustration No. 1, which shows a locomotive frame-stay in position on a 12in × 4in. hiloplane at Hillside. The operations for the machining of a frame-stay are as follows:—
No. 1.—A special tool-bar is provided for each head. After the frame-stay has been placed page 33 in position and bolted ready for machining, both tools are brought to the centre of it; the heads are then fed (with the depth of feed required) apart from one another (i.e., from centre of radius) under power traverse, and at the same time the slides, operated by the power traverse, are fed upwards (by hand) by a rotating wheel on the feed shaft. The upward course of the tools is followed on the two specially scaled rules, a close-up view of which is shown in illustration No. 2. This arrangement halves the cutting time, as both heads are operating simultaneously.
No. 2.—In operation No. 2 the top exhaust seating is machined with one tool.
No. 3.—In operation No. 3 the two side posts are brought into operation in the same setting, and the frame seating is then machined. (This operation also halves cutting time.)
No. 4—In operation No. 4 the frame-stay is turned upside down, and the bogie centre seating is machined. This completes the planing operations.
The actual machining time for the radius of the frame-stay under the new method is 16 hours. Hitherto this work alone occupied approximately 32 hours.
Under the old method it was necessary first to place the boiler into position, then level it and scribe the radius of the frame stay off the smoke-box. Then the boiler was removed and the frame-stay chipped as required. The boiler was then tried in a second time. If necessary, as was usual, the boiler was again removed to enable any further lumps on the frame-stay to be removed. The smoke-box would be secured by four bolts only for the first try in, after which it would be adjusted. On removal the remaining holes in the smoke-box and tubeplate landing would be drilled and the smoke-box could then be rivetted to the boiler. (During these operations the whole sequence of the work was held up.)
Under the new method the smoke-box is finally rivetted to the boiler, and the boiler (which has been previously lagged and completed) is placed in position, it being only necessary to square up the boiler at the back end. In this position the bolt holes in the saddle and smoke-box can be drilled and the bolts fitted.
The saving of time by the new method is approximately 200 hours. A wonderful improvement over the old methods has thereby been effected, and the installation of this modern type of machine has been fully justified.