Machining and assembling the front axle
This description of Ford practice in finishing front-axle components and carrying them to final assembly supplies a concrete example of actual machine-shop results obtained by carrying out certain definite principles. These underlying principles are: (1) A broad survey of the field of effort with a wholly free and unfettered mind. (2) The careful examination of existing conditions. (3) The elimination of every needless muscular movement and expenditure of energy in the shop-production routine.
What is more, these demonstrations of Ford practice show the ultimate results of ideal factory conditions—conditions in which there is absolute freedom both from any restraint of individual effort toward labor-cost reduction, and from that still more often imposed limit, the inability to incur necessary money cost. It happens that the Ford shops have several capable engineers working together in perfect harmony, and that these men of ideas are so fortunately placed that the cost of changes and improvements need have no determining influence whatever on the carrying out of new methods and means by them devised.
Aе the date of this writing, June 9, 1914, the Highland Park shops are working altogether fifty-nine men in the tool and fixture drawing room, forty pattern makers and four hundred and seventy-two tool makers, and there are besides these, three hundred men in outside machine-tool shops—say a total of eight hundred and seventy-one men employed in reducing to practice two broadly new methods of lowering Ford shop-production labor-cost, viz., by the placing of work slides of greater or less length, and by the use of the moving assembly. In addition to this work on installations which are supposedly new, the Ford shops are simultaneously completing the moving and replacing of more than five hundred machine tools to carry out what is termed in the Ford shops "progressive production"; that is to say, the scheme of placing both machine and hand work in straight-line sequence of operations , so that the component in progress shall travel the shortest road from start to finish, with no avoidable handling whatever.
In other words the Ford shops at this time present a large-scale laboratory demonstration showing results which conform absolutely to the theorems formulated by Professor Jones and Mr. Knoeppel.*; It certainly is not often that theory and practice, abstract reasoning ana the results of such reasoning in actual working form, can appear in one publication in such prompt succession and in such convincing coincidence.
The finishing of Ford front-axle components with work-slide installations , and the front-axle preliminary and final assembling lines, are of course purely technical examples of advanced machine-shop practice; but it is this very fact which makes this actual shop-practice story available as a demonstration of the correctness of the labor-cost reduction theorems formulated by Professor Jones and Mr. Knoeppel. Again, while it is undeniably true that thought must precede action, and right thinking alone can show the road to right doing, it is also undeniable that the sight of the actual right machine working in the right manner is far more impressive to the rank and file of "industrial economists," the practical shop-men working to reduce shop labor-costs, than any printed words can ever be; and because of this a fully illustrated story of ultimate shop practice, like this description of Ford front-axle production, has a highly efficient educational value of its own, because an actual presence is more impressive than a mental conception.
The study of the finishing and assembling of front-axle components shows how labor-costs may be very greatly reduced by three expedients: (1) By placing tools and men in operation sequence, so that each component shall travel the least possible distance while in process of finishing.
(2) By the use of work slides, placed so that upon the completion of one operation the workman can drop the component in one unvarying place, convenient to his hand, and so that gravity shall carry the component to within the easy reach of the workman who is to perform the next operation on the component.
(3) By the use of sliding assembly lines, chain-driven for the final assembling , but having the partial assemblies moved by hand.
This front-axle assembling job also shows one original machine tool by which two hand operations and one machine operation are ingeniously combined, and the moving assembly line is the latest Ford installation of that class, and shows some labor-saving peculiarities of much importance.
The illustrations given herewith show the complete front-axle assembly , a sectional view of the stub-axle and spoke flanges and the ball bearings, a floor-plan of the machine-tool placing for finishing of components , a sheet of rough and finished drop-forged components with their symbols, and many pictures of component finishing, together with views of the various novel aids in assembling.
Ford's Globe-Jointing of Axles
The Ford Model T car places a half-elliptic spring, convex side up, on each axle, and perches the chassis frame on the tops of these halfelliptic springs, which are shackled to the front axle and to the rear-axle housing. The rear-axle housing is prolonged to a forward globe-end, which is taken by a globe bearing, fixed to the chassis frame. The front axle is fitted with two horizontal diagonal braces, reaching to rearward, ending in a globe, and this globe is seated in a globe bearing , also fixed to the chassis frame.
The ends of the springs can safely endure a very considerable torsional flexure; hence the spring-hangers, or shackles, which secure the spring ends to the axles, are brass-bushed, with closely fitted pins and oil cups, all with the highly desirable result of making the car of this model extremely well adapted for the roughest of rough-road work; in point of fact the Model T car can stand a twist of 24 inches in its wheel base, 12 inches for each wheel above or below level, on contrary sides front and rear.
Ford's conception* of the low-cost car for the average man included the necessity of good performance on bad roads, or no roads at all, and this requirement was met by globe-jointing the axles to the chassis frame, thus giving the car the power to run over any surface, no matter how rough, whereon the motor could be made to turn the wheels without injury. This unique conception for satisfying the engineering requirements of the problem will be yet more fully understood from an inspection of the illustration on page 161.
The front-axle body, T-202, is milled on a large and very peculiar Ingersoll milling machine having a hand-revolved and machine-fed work-carrying fixture, of which two views are given. The feature of prime novelty and interest shown in this front-axlecomponents finishing job is the work slides, placed wherever they can be of obvious advantage and in many places where they seem at first sight to be needless, yet in every instance making large labor-cost reductions, some of which are specified later in this story.
TOf course, speaking broadly, there is nothing new in the use of troughs by which material or components under construction are moved by gravity from one location to another location. But the placing and using of such metal troughs, or "work slides" as they are here named, in the manner in which they are now (since 1913) placed in the Ford shops, is new to me, and the labor-savings effected by these work slides are incredibly large—vastly greater than at first expected by the Ford engineers themselves, who believed that the general use of these work slides would be advantageous, but had no expectation of such unbelievable labor-cost reductions as followed work-slide installation in every instance. The true cause of these labor-cost reductions is now known to be the saving of thought and of muscular movements gained by furnishing a fixed point where the workman may drop a component when his operation thereon is completed, and a second fixed point where the workman who is to perform the next succeeding operation can certainly pick up the piece when he wants it. This is the whole story, and the Ford engineers are now placing these work slides everywhere, always with marked reductions of labor costs.
The second astonishing feature shown by this front-axle job plant is the inverted drillers, shown working, front elevation, on page 168, and commented upon at length elsewhere.
The third notable machine-tool novelty shown on the front-axle component-finishing floor is the large front-axle body T-202, milling machine, shown in three views, page 165 front, and page 166 right end and rear. Of course, there is nothing broadly new in fitting a multispindle milling machine with a revolving work-holder; but the large size, peculiar construction, and excellent performance of this front-axlebody fork-and-spring-perch milling machine, supplied by Ingersoll to Ford engineers' specifications, give this tool novelty and interest. There are four mill-carrying spindles overhead, each of the outside spindles carrying four pairs of straddle mills adapted to mill the fork bosses of two axle bodies at once, while each of the inside spindles carries two pairs of straddle mills to mill the four spring-perch seats of two axle bodies at the same time.
The axle bodies are clamped to a revolving work-carrier which has four faces at right angles to each other, these faces being long and wide enough each to take two axle bodies laid flat, side by side, and leave room between the axle bodies for the straddle mills on the four mill spindles to work.
This large and heavy hand-revolved axle-body fixture has journals at each end, carried in slides which are moved up by action of an underneath cam-shaft, driven by worm-gear and tangent-screw, and has also a large capstan wheel at the right end by which the fixture may be handrevolved ; the fixture can be latched in four positions, 90 degrees apart. The four flat faces of this revolving and lifting horizontal work-carrier are provided with studs, clamps, and nuts at each end to hold two axle bodies on each flat face of the carrier, the pair of axle bodies being located on the carrier faces by two swinging spotting fixtures, one at each end, which are jointed to the end frames to swing in a horizontal plane. This work-carrier is counterbalanced by two 1,200-pound weights, suspended from chains which pass, over two idlers for each one and then take hold of the slides in which the revolving fixture is journaled.
Two workmen, one at each end, fix two axle bodies to one fixture-flat standing vertical before the men, locating the position by the swinging spotting fixtures and fixing the two axle bodies to the work-carrier by means of the clamps, studs, and nuts. Then the spotting fixtures at each end are turned out of the way, and the man at the right unlatches the revolving fixture and gives it a quarter turn by means of the capstan at the right, and then latches the fixture in position, the four millcarrying spindles running continuously. The man at the left then starts the cam-shaft ninning, and the cams lift the fixture, carrying two axle bodies clamped to its top horizontal flat face, up to the straddle mills, soap and water lubricated, and feed the cut up to top position, when the cams permit a quick gravity drop of the fixture, the cam-shaft drive being automatically knocked off when the fixture reaches low position. Meantime the two men have fixed two more axle bodies to the next vertical face of the work-carrier in front of them, as before, and when the work carrier rests in low position the man at the right again indexes the work-carrier a quarter turn, front side moving upward, and then the man at the left again starts the cam-shaft, all as before. At the fourth indexing of the work-carrier the men have to take off two milled axle bodies before they can place two more on the vertical flat of the carrier in front of them, and so on.
At first all the journals were oiled by individual oil-cups, time wasters and uncertain in action, which were soon changed for automatic, 25-lead mechanical oilers at each end of the machine, best shown in the right-hand end view.
The four mill spindles are worm-gear- and worm-driven, as shown in the rear view, which also shows the worm and worm-gear drive of the cam-shaft, the belt drive of the soap-and-water return pump, and the belt drives to the automatic oilers. There is no return of the lubricating oil, which runs down into the machine base. The work-carrier balanceweight chains are shown at each end in the rear view, taken with the machine in work. The front view was taken with the machine idle, because the flood of soap and water applied to the mills in work runs over the fixture and obscures details.
One grinding of the gangs of mills of this milling-machine will mill from 150 to 175 axle bodies, T-202, to within gauge limits. The gangs of mills are on individual arbors, so as to be removed from the machine and replaced as unit assemblies. Five tool-grinders are constantly em ployed in keeping up these gang-mill assemblies, several complete sets of which are used, so that there is no delay in changing. The regular practice is to change these gang-mill assemblies once in four hours, removing them from the milling machine before the work shows any sign of not being within gauge limits.
Speaking from the toolmaker 's side of this axlebody milling job, there is no uniformity of mill-life for "once grinding." The best record is four-days work for once grinding: poorest, part of one axle only, a hard axle taking the edges off six pairs of the straddle mills before completing the first cut. The grand average is about four-hours life, changing the gangs of mills twice in each eight-hour day.
This machine finishes the twelve surfaces on each of two axle bodies, twenty-four cuts in all, at the same time, and turns out about 450 milled axle bodies in eight hours, with two men, and uses about one pint of lubricating oil per hour. Three other milling machines of different forms are now used to bring the milling up to 900 axle bodies in eight hours, but these will soon be displaced by a second machine of the same general design as this with many changes and improvements, the two Ingersoll machines together being expected to mill about 1,000 axle bodies in eight hours. The holes are first jig-drilled to rough diameters, then the jig-bushes are changed to finish diameter, and the drills are changed for reamers to ream the holes to finish diameter. One man on this four-spindle driller drills and reams six holes in each one of about 130 front-axle bodies per eight-hour day.
It is a proverb among specialtool designers that a man will walk round and round the best method for any job and not see it for a long time, if ever. The more common event is that some other man, a stranger to the job, finally discovers the one best scheme. The spring-perch seats in this axle-body drilling job are about 2 1/2 inches through, and the chip-clearing spiral of the drills clears the hole of lubricant just as surely as it carries the chips upward, thus forcing the drills to work dry in heat-treated stock and making a very hard job indeed, almost as bad as the stub-axle hub-drilling.
Suppose the same general form of a horizontal work-carrier as that on the axle-body milling machine were used, stationary axis, no rise and fall action, with, say, the lower third of the horizontal -axis-fixture diameter submerged in lubricant, and suppose the lubricant reservoir to be fitted with four horizontal driller-quill resleeves , in which eight driller quills were spiral-gear-driven, drills at right angles to the fixture axis, and the correct distance below it, the four spindles on one side to carry drills and the four on the other side to carry reamers. Then all the drill and reamer work could be submerged and perfectly lubricated, the reamers following the drills back, and the workman having nothing to do save to index the fixture round and put on and take off the finish-reamed axle bodies. Then this drilling and reaming job would be performed under the most advantageous conditions, with a large reduction in first cost of the drilling machine, a saving of drill wear, and considerable saving in labor cost.
One word here as to the practical designing of special labor-costreduction machine tools.
It is a common saying among shop men that "everybody takes the hardest way first," and every machine-tool designer can recall many an instance in his own work where a later idea was much better than the first one, although the first idea was so good that it was eagerly reduced to practice in a greater or less extent before the unsought, later, and better scheme forced itself upon the designer's attention with the result of throwing away the previous work. To avoid such unpleasant events it is surely time well spent, before beginnings drawings, to consider fully and impartially every plan and method which might possibly serve the occasion, no matter how strange or absurd the plan appears at first sight; and such consideration of seemingly unavailable methods should not be superficial, but most careful and painstaking. It is excellent practice, when undertaking a new construction , to write, in full detail, every thought and scheme that can be mentally evolved before going to the drawing board at all, and the designer who follows this practice will very seldom find that he has wasted any time by delay in using the T-square and scale.
The "inverted drillers" used for drilling the stub-axle hub-holes (time 3 1/2 minutes, drill lubrication, drill spindle and drill feed underneath , with work-cooling overhead and drilling from one way only) might have been amplified and changed as follows, and probably would have been so changed had the conception occurred to the designer: The 3 1/2 minutes drilling time is more than twice the time of any other machining operation on the "steering spindle," or stub-axle. The stub-axle hub is strong and gives plenty of hold for chucking; hub axis and spindle axis might both be horizontal, the stub-axle to stand still and be completely finished, except the split-pin hole, at one chucking only, the hub to be drilled from both ways at once, reducing drilling time to, say, 100 seconds, the axle being finished while the axle hub is being drilled and reamed, and all cuts made submerged in lubricant.
This method of chucking and finishing avoids placing the stub-axles A self-opening threading die is fixed to the free end of an arm jointed to the tail spindle, to swing in an approximately horizontal plane through the live-spindle and tail-spindle axis. The tail-spindle is moved by a hand lever. When T-270 or T-282 is turned ready to thread, the workman moves the threading die to concentricity with the blank to be threaded and then starts the die on the work by pulling the tail-spindle hand lever. When the tail-spindle reaches its stop, the dies open, permitting the tail-spindle to be drawn back and the die is then pushed out of the way. This rig threads T-270, T-282 without reversing the lathe spindle on lathe centers, hence avoids centering, and could be made to finish the stub-axle with a considerable saving of time, all cuts submerged in lubricant.
The "inverted drillers," shown in the illustrations, direct an upward jet of lubricant to the bottom end of the hub, but cannot possibly give effective drilling lubrication through the entire length of the stub-axle hub-hole. Where a piece is submerged in lubricant atmospheric pressure ensures the presence of lubricant at the tool cutting edge, constantly, all as is well known and commonly practiced. In these "inverted drillers" all the lubricant jet from below can do is to lubricate the drill jig-brushing and the point of the drill when starting.
To keep the hub cool as may be while being drilled, a large jet of soap and water lubricant is directed on the exterior of the hub from above. This exterior cooling of the stub-axle hub while drilling the ^-inch diameter pin hole makes it barely possible to drill this ^-inch hole through 4^ inches of heat-treated steel with ordinary twist drills, and to drill these same ^8-inch holes with "Celfor" twist drills with some degree of comfort, though Celfor drills work much better on this job with drillers of the ordinary form, spindle and lubrication both above the work, than with the "inverted" drillers.
This comment and suggestion is an unavoidable result of inspection of the unique and most surprising "inverted" drillers used for the larger part of the stubaxle pin-hole drilling. It is not uncommon to place drill spindles underneath the pieces to be drilled, for convenience in submerging the work in lubricant and so forcing the lubricant by atmospheric pressure to fill the hole and follow the drill cutting edges as they enter the metal; but in these "inverted drillers" the work is not submerged, and the drills are not lubricated, but are forced to drill 4J^ inches through the heat-treated steel absolutely dry, with no lubrication whatever, and depend upon exterior cooling of the work to make the drilling possible. Such a job could not be passed without special mention, because it shows drilling practice not to be seen, probably, anywhere else in the world.
Ford Front-Axle Component Finishing
Neither brass bushes, connecting-rod bodies, nuts, nor stub-axle pins are shown in the plate of components on page 163, and all stock has the following list of operations, as may be needed, performed upon it before being brought by monorail to the front-axle components finishing job, viz.: heat-treat, anneal, rough-straighten, finish-straighten, snag and tumble.
The front-axle body is first of all inspected for straightness, and such bodies as are not satisfactory in this particular are returned to the heattreating department for correction before beginning machine work on this component.
Here follows the long list of finishing operations on components shown on the components and symbols sheet, page 163. The name of each operation is followed by the name of the machine used for performing that operation, the number of working spindles of the machine, the number of men employed upon the operation, and the operation time. This list is given in full on the following pages.
Two forms of drillers are used for drilling 5/8-inch holes with Celfor drills in the stub-axle hubs, one form having the drills below the work, while the other form, not shown in the illustrations, has the drillers above the work, both forms being used with flooded soap-and-water lubrication, which is more effective for the slightly greater depth with the drill above the work than with the drill below the work. In point of fact, however, these Celfor drills work dry in steel dropforgings , heat-treated for maximum strength and toughness, which means also maximum resistance to drilling.
The Celfor drills, 5/8-inch diameter, are driven at 430 revolutions per minute. The length of hub is 43^ inches, and from 30 to 70 hubs (from 135 inches to 315 inches length of hole) are drilled dry for once grinding. The drills hold their cutting edges to the last instant of work; then the edge goes, the drill clearance is instantly snubbed off, the drill point is blued, and in some instances the outer drill-edge corners are rubbed off for as much as l/4 inch;.generally the corners are gone for about Vi6 inch. The drills are not re-ground past the bluing, but only far enough to bring the corner into good form. Ordinary twist drills give so much trouble in this job that were it not for the Celfor drill the forms of drilling machine used would not serve.
Spring Hangers—T-246, T-91 1/2
The front- and rear-axle spring hangers are nearly alike, the rear-axle hangers being longer to take the wider spring. For good reasons the rear-spring hanger, T-9l3^, and front-spring hanger, T-246, operations are here listed together, total production 6,400 per eight-hour day.
Front-Axle Components Finishing Department
July 9, 1914, this department was working about 375 men, graded according to efficiency in four grades, numbered 1, 2, 3 and 4, grade No. 1 being of lowest efficiency and No. 4 of highest efficiency. The grade number of a man does not determine his hour wage. A No. 1 man, lowest-efficiency grade, may be paid $5.00 for 8-hours work, and a No. 4 man, highest-efficiency grade, may be paid $2.80 for 8-hours work.
Again, in reducing department force of workmen, the ordinary management would, of course, prefer to keep No. 4 men and let No. 1 men go. Under the present arrangement of affairs those men having most individuals dependent on their wages for a living are given most pay, regardless of efficiency rating, and in letting men go those having the more individuals to support are likely to be retained, regardless of efficiency standing.
The front-axle components finishing department is in charge of one foreman, who has two assistant foremen, three clerks, and one "straw boss" for about every 20 workmen, besides tool-setters who are machinists of intelligence, experience , and all-round reliability. The foreman is, of necessity, a competent mechanic and a competent administrator. The department records are kept on three form blanks; Form 915, Production Time Ticket, Form 552, Report of Stock Machined, and Form 858, Individual Workman 's Production Record, an index-card form.
Productive Time-Ticket, Form 915
Form blank 915 is a stiff manila card 3 11/16 inches wide by 6 7/16 inches high, printed in black and red on one side only, "K-17, Front Axle Parts, C," the date being printed in red. Each workman keeps an individual record of his own day's performance, and these records are gathered by the straw bosses and transferred to Form 915, each man's work record on an individual card at the close of each day's work, and delivered by the straw boss to the two clerks who fill forms 552 and 858 from the forms 915.
Workman's Individual Production Record, Form 858
This is a stiff index card, yellow in color, printed in black, ruled in red and green with the 31 lines of the workman's record, in three principal divisions, giving space for 93-days record; size 8 inches wide by 5 inches high. It is filled by a department clerk from Forms 915 with the calendar month's record and sent by the department clerk to the cost department, where labor cost and time of production totals are taken from those forms 858, which are preserved for six months and then destroyed.
The capital letter "B" in the upper left corner of the form reproduction is the work-hours shift symbol. Working one 8-hour day only the shift symbol is "B-1," contracted to "B" on card. Workmen go on at 6:30 a. m., stop 10:30, take 30 minutes of their own time for lunch, go on again at 11:00 a. m. and off for the day at 3:00, making an 8-hour day.
Working two shifts, the shift symbol for the first shift is "B-l." On this basis the men go on at 6:30 a. m., stop 10:30 a. m. for lunch, 30 minutes of their own time; on again at 11:00 a. m., off at 3:00 p. m., an 8-hour day. The second shift, with the symbol "B-2," goes on at 3:00 P- m., off at 11:00 p. m., with gift of 15 minutes, 7:00 to 7:15 p. m., for eating. Working three shifts, the shift symbols are "C-l,"—on at 8:00 a. m.,
off at 4:00 p. m., with gift of 10 minutes for eating from 12:00 noon to 12:10 p. m.; "C-2,"on at 4:00 p. m., off at 12:00 midnight, with gift of 10 minutes from 8 to 8:10 p. m. for eating; "C-3,"on at 12:00 midnight, off at 8:00 a. m., with gift of 10 minutes, 4:00 to 4:10 a. m., for eating. These allotments of shift working hours are made to equalize demands on shop driving-power.
Departmental Report of Stock Machined — Form 552
Printed in black, on white, thin paper, size 5 1/2 by 12 in. Because the "Requisition" is for the whole year round, one year after another, the "Requisition No." column is not used, and because the entire Ford shops production is "Model T" cars, the "T" is not written, and because the symbol, as "T-202," carries the component name with it, the "name" space is not filled.
Forms 552 are filled, as shown on page 182, by a department "C" clerk, from the productive-time ticket Form 915, in pencil, one original and two carbon copies, one copy being sent to the "division foreman," next above the department foreman, one to the "machine-shop foreman ," next above the division foreman, and one copy to the head of the "finished stock" (components) records department. Card-index records of individual-component production are made from these forms 552 by clerks in the machine-shop foreman's office and in the finished-stock department. From the front-axle components finishing department, work goes to the front-axle assembling department, symbol letter "A," by monorail.
Front-Axle Assembling Department
The officials are one assembling-department foreman, one assistant foreman, one straw boss, and one clerk. The form blanks, filled by the clerk, are as in Department C. The assembling department assembles the front axles, paints them, bakes them, paints them a second time, and bakes them a second time, using doors on the west side of the ovens, and then, through doors on the east side, removes the finished axles ready for the assembling line. The assembling department works 44 men in each shift to turn out 800 axles, double shift 1,600 axles, three shifts, 2,400 axles. One man is a stock handler, one man is a floor sweeper, 30 men work as actual assemblers, and 10 of the assemblers work on the movingassembly line. The list of operations necessary to the front-axle assembly is as follows:
- 1. Assemble minor No. 1 and No. 2 to T-202 axle with two T-211 spindle bolts.
- 2. Screw in T-211 bolts to minor No. 1 and No. 2.
- 3. Put on two T-60 nuts, and two T-763 cotter pins to T-211 spindle bolts.
Small globe finishing is by a grooved tool at the back, pulled forward to a stop by screw and handwheel , for the rough turning. The finish turning is by a shell tool with a notch for the globe-neck. The ground internal cylindrical bore of the finishing tool has its working annular face ground to a 7 degree angle, the bore being same diameter as the finished globe. About 150 globes are finished with one grinding of the finishing tool. This cylindrical finishing tool is carried on the free end of a rectangular body, confined in a slot in a tool-holder fixed to a cross slide, the out-end of the rectangular body being pivoted to swing up and down in the holder slot, so that the cylindrical tool has an automatic vertical adjustment to suit the globe vertical position. The roughing tool leaves the globe about ten thousandths oversize, and the finished product is very close to a sphere
- 4. Assemble minor No. 3 to minor No. 2 with one T-216 bolt.
- 5. Adjust minor No. 3 and tighten T-216 bolt to minor No. 2, put in one T-216 bolt to minor No. 1.
- 6. Put on two T-220 nuts and tighten up with two T-753 cotter pins to T-216 bolts.
- 7. Assemble minor No. 4 to T-202 axle with two T-242 nuts.
- 8. Tighten up two T-242 nuts and put in two T-82 cotter pins.
- 9. Tighten up two T-77 radius-rod nuts and put in two T-82 cotter pins.
- 10. Tighten up four spring hanger nuts T-242 and put in four T-88 cotter-pins.
- 11. Tighten up connecting-rod yoke bolt-nut T-8 and put in one T-82 cotter pin.
- 12. Paint.
- 13. Bake.
- 14. Paint.
- 15. Bake.
Only two of the minor assembling operations are shown in the upper picture on page 192. In this view, the middle workman is pressing the inside ball-bearing cone onto the stub axle, using for the purpose an ordinary hand-lever arbor press. The man at the right does not come into this story. In the right middle of the picture is seen a small machine, belt-driven, with a chuck
The work is on one fixed and one spring center, and is so driven that work automatically drops down when tail center is drawn away, and thus clears the machine to take the next piece. Wheel slide is run to a stop, set by the tool-setter after truing the wheel. 225 to 250 pieces are ground at one slidesetting , 1,300 to 1,400 pieces for one man and one grinding machine in 8 hours on the spindle nose, formerly used to run the nut on T-270, T-282, after being pressed into the stub-axle steering-arm hub. The assembling of the steering arms and stub axles was formerly as follows: First, with arbor press, force arm into hub eye; next, with small machine on bench, run the steering-arm holding nut on; and third, adjust this castellated nut by hand so that the splitpin could be placed.
These three operations are now performed at one single handling, on the machine shown at the left on page 162, which is curious, inasmuch as it combines two hand operations and one power-driven operation, with marked time sav ing. This unique machine is a rack-and-pinion arbor press, having a fixture to take T-270 or T-282 on the press vertical-spindle bottom -end, set on a base which contains an electric motor at the bottom from which a vertical spindle on the workman's side is friction -driven, this running verticalspindle top-end, directly under the threaded end of T-270 or T-281 held in the press-slide fixture, being fitted to take the hex-nut which holds the steering arm home in the stub-axle hub boss, so that the nut is running friction-driven when the workman, having placed the steering arm in the press-slide fixture, next places the stub axle in a fixture under the press slide, ready to take the steering arm. Next, the workman forces the arm home to the shoulder in its stub-axle hub seat, the power-driven nut being simultaneously run home on the steering-arm thread by the frictiondriven vertical spindle. The lower power-and-frictiondriven nut-spindle has fixed to its top end a double-acting ratchet with a horizontal lever; the workman holds the press lever down.
All the Ford chain-driven lines use the chain and sprockets of the Link Belt Engineering Company, Chicago. The speed of each assembling line must be brought to suit exactly the work performed on it. This chain moves at a speed of 14 feet per minute. The drive is from an electric motor on the ceiling, belted to a first counter-shaft, thence to a second overhead counter-shaft, thence by a cased-in vertical belt to a pinion-shaft on floor hangers, from which the sprocket-shaft is driven by enclosed pinion and spur-gear. The floor hangers stand on sections of I-beams to bring them to height Three components, the rod, the ball-wrist T-226 and the fork, T-227 are united by pinning and brazing.
The globe-wrist stands at 90 degrees to rod axis, and prevents the assembly from turning when dropped into the testing-block slot. Then a heavy handled wrench is applied to the fork and moved rapidly so as to give strong torsion blows in both directions with sufficient force to rupture the brazing if imperfect with his right hand, the nut screwed home to the boss-end holds the friction -driven vertical spindle still, and the workman then grasps the double-acting ratchet lever with his left hand and, as shown in the picture, bends his head down and with the ratchet adjusts the castellated -nut notches to the split-pin hole in the end of the steering-arm screw thread, all in about five seconds time.
It should be here noted that in hand-work time is saved by dividing operations, while exactly the reverse is true in automatic-machine work, where time is saved by combining operations performed at one setting or chucking of the work. The steering-arm and stub-axle assembling machine is the first to come under my observation in which power-driven and hand-made adjusting operations are combined.
West of the assembly line are two drill presses, spindle frictiondriven , by which the stub-axle pins are driven into the threaded lower fork-bosses, making the axle ready for the chain-driven assembly line. The lower picture on page 191 shows the middle part of the chain line, with a bridge over it. This bridge carries on top a full-length fixture which takes both stub axles and holds them in line while the steering-arms parallel-connectingrod is placed and adjusted to length, so that both the front wheels will stand in straight-ahead running position at the same time. This bridge is elevated and its supports clear the full length of the assembled front axle.
Those axles which are to be sent to the Ford "branches," do not have the steering-arm parallel-rods fitted, as the length-adjustment of this rod would be lost in "knockingdown."
Axles to be placed in chassis assembly at the Highland Park shops are lifted up off the chain-line, placed on the bridge, and have the parallel rod placed as described, and are then lifted off the bridge and placed on the chain-line slides again, all as seen in this illustration.
The upper photograph on page 191 is a view of the south side of assembling fine, looking west-north In assembling the steering arm and stub-axle there are two operations to be performed: (1), to press the arm into its seat in the stub-axle hub boss; (2), to screw the nut on the threaded end of the steering arm. The castellated nut must be turned so the split pin can be seated west. The foreman of assemblers stands at the left, attentively watching work in progress.
The work turret is revolved by hand by the workman at the left, who takes the work from the turret support as soon as the joint is brazed. The man at the right applies borax paste and places short piece of brass wire about J^-in. diameter in drilled hole against the rod end, and then places the job on the turret supports. As the turret is revolved the braze joint passes through a gas-flame-heated arcshaped top chamber
Page 194 shows the painters at work; 800 axles are handled off the line, painted, placed in the ovens seen at the rear, baked, taken out, painted again, baked again, ready to be removed from the far side of the ovens, all at the rate of 100 axles completed per hour.
Former Front-Axle Assembling Practice
January 1, 1913, the final assembling of the front axles, after sundry minor assemblies had been made up, was carried on by providing each assembler with a vise of his. own, all final assemblers being placed at one long, sheetmetal -covered bench. The assemblers were competent mechanics and the front-axle assembling job was regarded as being in pretty good form.f With 125 men, all told, 450 front axles were assembled in one 9-hour day, not painted nor baked, j This was at the rate of 1,125 hours for 450 axles, or 2 hours 30 minutes of one man's time for assembling each axle. I January 1, 1914, things were better; 90 men in an 8-hour day, assembled 650 axles. The rate was 720 hours for 650 axles, or 1 hour 6j/£ minutes of one man's time for assembling one axle—less than onehalf the January 1, 1913, time.
A new machine; front view from workman's side with vertical spindle cover removed. The vertical spindle is driven by a bevel gear and pinion (not visible in the picture) from a motor in the machine base. The photograph shows the friction spring and friction disk above the bottom journal of the spindle and the nut-positioning ratchet lever above the top bearing of the spindle I The moving-assembly line began working June 1,1914, and this day, July 13,1914, 44 men, all told, are assembling, painting, and baking 800 axles in one 8-hour day, giving a rate of 352 hours for 800 axles, or 21.120 minutes—say 263^ minutes—for one front axle. To recapitulate: January 1, 1913, axle assembling, 150 minutes. January 1, 1914, axle assembling, 663/2 minutes. July 13, 1914, axle assembling, 26^ minutes.
The painting stands are placed close to the eastern (delivery) end of the assembling line. The axles are painted as soon as they come off the assembling line, are lifted from the painting stands and piled in the baking ovens, baked for 30 minutes, taken out, painted a second coat, and baked again for 30 minutes, and are then taken from oven doors on the other side of the ovens, directly to the chassis-assembling line. All of which shows, beyond question, that by use of a few new ideas and some hard work, machine-shop labor costs, in some instances, may be very materially decreased. While the Ford engineers cannot justly be said to be puffed up with the successes of their efforts, they are really disposed to claim having produced at least one single example of that extremely rare exhibit, a 100 per cent efficiency installation which produces the Ford Model T commutator.
This small construction does not involve the use of the movingassembly line, but it does involve one initial feature of absolutely novel machine-shop practice, so far as my personal observation in work of this or similar character goes.
The Ford commutator construction, prefaced by one or two of the more striking 1914 work-slide installations of the Ford shops, will be described in the next chapters—certainly the most surprising labor-cost reduction data ever printed, considering the simplicity of the original conceptions which are shown to have paved the way to the incredible savings gained.