Document ppQXYJpeZXjBM7oKV3x5XGmJD

0 Slolrwoy power* unit, Hn o tqulrrol-cogo motor M ond broke B supported " Irom lower holf ol wo'm-and-geor housing, a rugged one-piece casting Q Power unit ilmilor to Fig. 6 but of rwiktv assembly for driving small moving stalrwoyifl ji Qy.fypo imoo'Mreod-tiep moving ilotrwoys required o 11 On modern stairways, comb teeth fit ctosaly between step V ihunt S or the landings to guide the passengers on end oft 1 1 cleots to form proctlcolty smooth surioce of the landing! i Hi ;k Moving-Stairway Story Continual between plates 0 by tension springs 5. As long os stairway operates normally, With Brake!, Drives, two magnets hold the pawls released Safety, Capacity and Speed from rings B and B,, so the whole brake ,, rotates with the drive-chain sprockets. When power is cut oft by opening a slop or safety switch, one magnet re leases its pawl into one of the pawl ere shown in Fig. 6 for one type of power end. In this unit the power 2strand roller chain runs on sprockets P and the handrail drive roller chains run on sprockets //, one for each rail. Sprocket C drives the speed governor. A magnetic brake between sprockets P and D stops the stairway when power is shut off. In Fig. 6, sprockets are 6xed on the axle and all revolve os a unit, whercos in Fig. 1 the axle is stationary and the ittp-cHaln sprockets revolve on it on roller bearings, Fig. 7. Chain-step sprockets D are rigidly connected together by a cast-steel spider or barrel housing BH, to which they are bolted to prevent misalignment. In Fig. 6, handrails are driven by sprockets fl at each end of the main drive shaft, but in Fig. 7 these sprockets ere on the barrel housing between the step-chain sprockets. Stolrwoy Brakes. On the driving ma chine, Fig. 7, two pawl-applied aeporstely.opersted brakes ere side by side on the right-hand step-chain sprocket. These have two pawl rings, B and Bu faced with friction material F and held rings. This stops the ring which slows down the stairway because of the brak ing action, but the other ring continues to rotate with the drive shaft. A few seconds later the second magnet re leases its pawl, which* applies the sec ond brake to bring the stairway to s smooth stop, fn this system both brakes operate each time the stairway stops, generally at least one a day. Orlvos. Moving stairways are driven at constant speed by a power unit that consists of a constant-speed motor and some form of speed reducer. In Fig. 1, the power unit has a single-speed squir rel-cage motor M, a service brake B, a speed governor C and a worm gear, similar to a worm-gear elevator machine. This machine is also built without a service brake. On It the brake on the step-choin sprocket acts for both serv ice and emergency steps. Other stairways are driven by a closely assembled motor, worm gear and brake of either horizontal or vertical construction. Fig. 8 and 9. Unit In Fig. 8 has a squirrel-caae motor M. end a brake B supported from the lower holf of the worm-gear housing, a rugged onepiece easting to give rigid support to the whole machine. An overipeed i underspeed governor G is driven d from the motor-shaft end. A drive-chain switch is at C. Vertical Drives. Power unit in Fig 9 is like Fig. 8, but is a vertical esicotblj for driving smaller stairways. It is do-* signed for installation in top end ri truss to save space ond reduce buildlii framing. A heavy single-strsnd rsflo chain connects the drive sprockets 0 on the machine to that on the stepchih; drive abaft. A recent dcvelopmenfhi s vertical squirrel-cage motor onevdra gear, whose gear shaft eofioects Vj helical geara to atairwoy drive shaft. : Safety. These stairways are the cafe* means of transportation even tboafh they are subjected to ell the prssb that human Ingenuity, curiosity cod carelessness can devise. They are nods safe for even the most careless ridttSt This is because safety has baco de signed into every port of the equip**-' Beginning with the steps, they hsir narrow groove treads of we4^re*^,I,a, 1 aluminum alloy that form a stable pisi form, comfortable to stand on. Spt* between the eleats on the step* h narrow shot soft eoles or narrow UP- heels cannot sink between them. 0* elearonces prevent dragging of g!*?* or boots between the treads end sx1 risen. Solid step risers and close ences prevent accidents as step f*1' lion changes. ' On old type flat-step moving stsir**P with smooth tread steps, o shunt 5. PLAN! OPERATION AND MAINTENANCE SECTION required at the landing to guide puxngrrs oo and off the steps. At the landing plate end comb for added safety when getting on and off. Besides, (he can be built, to about 80 it, they con be operated in series so that they will serve fefdioi cod of modern steirwoys the top come out from under a comb fkts, M * C. Fig. 11- The comb teeth 'll yiih close clearance between the -cleat treads to form practically a h surface. - ``IKsthtet safety features are the ample .Imd spaces formed at the landings by .tks 2-ctep tread 7*. nearest the comb pUts.` When In this level position the , tvs idjscent treads fit so closely to- ;piker that there Is no space or groove h which to snag a heel or catch the -^pekit ef sn umbrella. . Ufsnded Nowets. Getting passengers va sad off s stairway Is one of the most stairway Is well illuminated for Its full length. In odditlon to the features that moke it safe to ride On a moving stair way, other safety, devices stop it if it is not in good operating condition. Capacity. For handling large crowd*, stairways hove many advantages, the first being their large capacity. A sin gle stairway 4-ft wide, operating at 90ft per min handles up to 6000 passengers per hour, whereas a large low-rise eleva tor serves only about 500. A stairway handles as many passengers on a 70-ft rise as on 12 ft. Height of rise Is e lim iting factor in the number of passengers that an elevator can handle. several floors. This practico is often used fn large department stores. This type of opera tion requires a transfer at each floor. This is not a serious objection in s store, because a large part of the traffic is from floor to floor. Stairways can be operated (1) ascend ing (2) descending (3) or In both diree* lions. To accommodate traffic peaks they may ascend for part of (he day, and de scend for the rest of the time. Higher Rise*. To adapt moving stair ways to higher buildings a system com bining express and local stairways was proposed by C B Cuirae in April 1952, faponsm problems in Its safe opera Moving stairways are not limited to rircAftecturof Record. Tn a 10-story tise. Semicircular newels, Fig. 11, at handling largo crowds. Frequently they building the express units would serve < tab landings contribute much to solv- are Installed for interoffice service, 1st, 4th, 7th and 10th floors. '.insthis problem. In Fig. 11 the newels where one company occupies mere than Thus a passenger could go from the - udbatunrade extend for some distance one floor. Moreover, when they connect 1st floor to the 10th floor and transfer Were the steps start to rise. For port the ground and second floors of an of only twice, compared to eight times on *> this distance the steps are under fice building, (be second is almost es the locals. Travel time on the express floor and comb plates, then come out desirable for renting as the first floor. Is 2 minutes, 31 seconds, on the local ' Jd run flt for two tread widths be-- In deportment stores they increase sales 3 minutes, 19 seconds. To go from the wrathey Hart to rise. In this distance, volume on all off-street floors by mak 1st to the 6th floor, a passenger would Ww can grasp the moving hand- ing them easily accessible ond reducing express to 4lh, take local to 6th, requir. [".before reaching the steps, and re- customer fatigue by eliminating waiting Ing two transfers ond 2 minutes, 47 sec [*" their grip nntll ofter they leave and crowding. These end many other onds to make the trip. jW?- This assists them to enter end factors have made moving stairways os Mr. Gusrae arrived tt the conclusion JJ the stairs smoothly and without popular as elevators for low- and In hfi article that besides lower deify ""^Ing, which proctlcolly eliminates medium-rise service in manj types of operating ooat with moving stairways, t* stumbling hazard on the steps. buildings. they do not require pea(houses, pits, Jait above the comb plate at each Stairways In Series. Even though complicated controls. They also need I'nainsl, a light l in the sides of the moving atalrweys are limited, In the teas floor space then elevators ef com nstiadea. Fig. 11, illuminates the height of o tingle rise for whieh they parable capacity, and they cost less. ' tf PUNT OPERATION ANO `MAINTENANCE SECTION 135