on main pin nor more than three-sixteenths inch on other pins.

(g) Switching locomotives. The bore of motor rod or main rod bearings on locomotive used in switching service shall not exceed pin diameters more than one-eighth inch at front end nor more than five thirty-seconds inch at back end.

(h) Bore of rod bushings. The bore of side rod bearings on locomotives used in switching service shall not exceed pin diameters more than three-sixteenths inch.

§ 91.216 Jack shafts.

(a) Jack shafts shall be properly counter-balanced; crank arms and discs shall properly fit and be securely fastened on shaft.

(b) When motor rods are direct connected to jack shaft crank arms or discs, the bore of shaft bearings shall not exceed journal diameter more than onesixteenth inch. When the motor drive is geared, the bore of shaft bearings shall not exceed journal diameter more than one-eighth inch.

§ 91.217 Quill drive.

(a) Quills shall have sufficient clearance for relative motion of axle and wheel. Drive pins shall be securely applied.

(b) Quills with any of the following defects shall not be continued in service: Cracked or loose drive pin; broken or defective quill coil springs; broken or defective quill gear spring seat, saddle or fastenings. § 91.218

Gears and pinions.

(a) Exposed gears shall be provided with safe and suitable guards.

(b) Gears or pinions with any of the following defects shall not be continued in service: Gear or pinion loose on shaft; broken, cracked, or with badly worn teeth; broken or defective rim fastenings; out of alignment or improperly meshed; split gears with loose or missing bolts.

§ 91.219 Driving boxes, shoes, and wedges.

Driving and other journal boxes, shoes, and wedges shall be maintained in safe and suitable condition for service. Broken and loose bearings shall be renewed. Not more than one shim may be used between box and bearing if bearing is pressed in box. Where shoes and wedges are not provided, total longi

tudinal clearance between journal box and pedestals shall not exceed 1⁄2 inch. [23 FR. 2218, Apr. 4, 1958]

§ 91.220 Lateral motion.

The total uncontrolled lateral motion between the hubs of the wheels and boxes, between boxes and pedestals or both, on any pair of wheels shall not exceed the following limits: Truck wheels, 1 inch; driving wheels, more than one pair of wheels, 3⁄44 inch. These limits may be increased if upon application to the director his investigation shows that conditions require additional lateral motion. The lateral motion shall in all cases be kept within such limits that the driving wheels, rods, crank pins, or armatures will not interfere with other parts of the locomotive.

Interpretation: The "total uncontrolled lateral motion" referred to in this rule means the lateral motion provided for in the design of the parts, plus any additional lateral motion due to wear.

[24 F.R. 476, Jan. 21, 1959] § 91.221

Frames and parts.

(a) Maintenance. Frames, deck plates, tailpieces, pedestals, braces, body bolsters, transom plates, body center plates and locking devices shall be maintained in safe and suitable condition for service and shall be cleaned and thoroughly inspected each time a unit is in shop for general or heavy repairs.

(b) Cleaning underframe. Underframe, trucks, fuel tanks and brake rigging shall be kept free of accumulations of oil, grease and debris that would constitute a fire hazard.

[23 F.R. 2218, Apr. 23, 1958] § 91.222 Spring rigging.

(a) Springs and equalizers shall be arranged to insure the proper distribution of weight, cushion the shocks to the various wheels, and be maintained approximately level.

(b) Springs or spring rigging with any of the following defects shall be renewed or properly repaired: Top leaf broken or two leaves in top half or any three leaves in spring broken (the long side of spring to be considered the top); springs with leaves working in band; broken coil springs; broken, cracked, or badly worn driving-box saddle, equalizer, hanger, bolt, gib, or pin.

(c) In absence of protective construction, safety hangers shall be provided which will prevent spring planks, spring seats or bolsters from dropping to track

(a) Center plates. Truck center plates shall fit properly and be securely fastened. The male center plate shall extend into the female center plate not less than 34 inch. On trucks constructed to transmit tractive effort through center plate or center pin, the male center plate shall extend into the female center plate not less than 11⁄2 inches. Center plates shall be securely fastened, and ones of the type requiring lubrication, shall be properly lubricated and maintained. Maximum lost motion in a center plate assemblage shall not exceed 1⁄2 inch. These limits may be adjusted if upon application to the director his investigation shows that conditions so require.

(b) Centering devices. Center pins with a substantial head, key, or nut at each end, or other suitable means, shall be provided that will hold the carrying bolster on the truck. All centering devices shall be properly maintained.

(c) Safety chains. A suitable safety chain of minimum consistent strength shall be provided at each corner of all four-wheel trucks except where construction prevents truck sluing in case of derailment.

(d) Clearances. All parts of trucks shall have sufficient clearance to prevent them from seriously interfering with any other part of the locomotive.

(e) Bolsters. Truck bolsters shall be maintained approximately level. (f) Radius bar pins.

Suitable means

for securing radius bar pins in place shall be provided. Inverted radius bar pins shall be held in place by plate or stirrup.

(g) Defects. Trucks with any of the following defects shall not be continued in service: Cracked arch bar; loose column, pedestal, or journal-box bolt; cracked or broken frame, unless properly repaired; loose tie bar; broken or defective motor suspension lug, spring, bar, or bolt; broken or cracked center casting; cracked or broken equalizer, hanger, gib, or pin.

(h) Motor suspension. Motor suspension lugs or bars shall be of ample strength and provision made that will prevent nose-supported motors from

failing in case of failure of motor supports.

[Rules and instructions for inspection and testing of locomotives, other than steam, and their appurtenances, I. C. C., Dec. 14, 1925, as amended Mar. 2, 1936; 23 FR. 2219, Apr. 4, 1958]

§ 91.224 Side bearings.

(a) Side bearings shall be securely fastened in place. Friction side bearings with springs designed to carry weight shall not be continued in service with more than 25 percent of the springs broken in any one nest.

(b) Friction side bearings unless designed to carry weight shall not be run in contact. Maximum clearance of side bearings shall not exceed one-fourth inch on each side, or a total of one-half inch on both sides, except where more than two side bearings are used under the same rigid superstructure, the clearance on one pair of side bearings under the same rigid superstructure shall not exceed one-fourth inch on each side or a total of one-half inch on both sides. The other side bearings under the same rigid superstructure may be one-halfinch clearance on each side or a total of 1 inch on both sides. These clearances apply where the spread of the side bearings is 50 inches or less. Where the spread is greater, the side bearing clearance may be increased in proportion. Side bearing clearances may be modified if upon investigation by the Director his investigation shows that operating conditions and construction warrant such modification.

§ 91.225 Clearance above top of rail.

No part or appliance of locomotive, except the wheels and flexible non-metallic sand pipe extension tips, shall be less than 21⁄2 inches above the top of rail. [23 F.R. 2219, Apr. 4, 1958]

WHEELS

§ 91.226 Wheels.

(a) Tight on axle. (1) Wheels shall be securely pressed on axles except wheels and axles of special design and construction where other proper and safe means are provided for holding the wheels on the axles. Prick punching, shimming wheel fit, or pins driven in ends of axles will not be permitted.

(2) Mill scale shall be removed from plate and entire wheel then inspected before application to axle. Wheels shall be kept free from accumulations of oil, grease, or other material that could conceal cracks or other defects.

Interpretation: The first sentence of the second paragraph of this rule requires that wheels mounted on axles on and after the effective date of the rule shall have mill scale removed before application.

The second sentence of the second paragraph is not intended to impose unreasonable requirements, but is construed to mean that wheels shall be kept reasonably clean, so as to permit detection of cracks and other defects in the course of normal inspection.

(b) Diameter. When wheels or tires are applied, or wheels or tires are turned, the diameter of the wheels on the same axle shall not vary more than three thirty-seconds inch. When all tires are turned or new tires applied to driving wheels in rod-connected driving wheel bases the diameter of such tires shall not vary more than three thirty-seconds inch. When a single pair of tires is applied in a rod-connected drivingwheel base the diameter of such tires shall be within three thirty-seconds inch of the average diameter of the other tires in the same driving-wheel base.

(c) Gauge. Wheels used on standardgauge track will be out of gauge if the inside gauge of flanges, measured on base line, is less than 53 inches or more than 531⁄2 inches.

(d) Variance back to back. The distance back to back of flanges of wheels mounted on the same axle shall not vary more than one-fourth inch.

(e) Divided rims. Wheel centers with divided rims shall be properly fitted with iron or steel filling blocks or autogenously welded before the tires are applied, and be properly maintained.

(f) Tire shims. When shims are inserted between the tire and the wheel center, not more than two thicknesses of shim may be used, one of which must extend entirely around the wheel. Shims which extend entirely around the wheel may be in one or more pieces, provided they do not overlap. Under no circumstances shall there be more than two thicknesses of shim at any point.

(g) Counterbalance. Counterbalance shall be maintained in safe and suitable condition for service.

(h) Flange height. On locomotives used in road service the minimum height of flange measured from tread shall be 1 inch and on switching locomotives shall be seven-eighths inch, except where construction will not permit the full height of flange on all driving wheels in any rigid wheel base the height of flange on at least two pairs of drivers shall be not less than 1 inch for road locomotives and not less than seven-eighths inch for

switching locomotives; the others may have flanges with minimum height of five-eighths inch. Where plain tires or five-eighths-inch flanges are used on front or rear drivers, trucks shall be provided for safely guiding the locomotive.

(i) Tread taper. The maximum taper for tread of driving wheels from throat of flange to outside of wheel for locomotives used in road service shall be onefourth inch, and for locomotives used in switching service five-sixteenths inch. The maximum taper for tread of truck wheels from throat of flange to outside of wheel shall be five-sixteenths inch.

(j) Tire width. The minimum width of tires for driving and truck wheels of standard-gauge locomotives shall be 51⁄2 inches for flanged tires, and 6 inches for plain tires. The minimum width of tires for driving and truck wheels of narrowgauge locomotives shall be 5 inches for flanged tires, and 51⁄2 inches for plain tires.

(k) Modification. The limits prescribed in paragraphs (c), (h), and (j) of this section may be modified if, upon application to the Director, his investigation shows that conditions warrant such modification.

[Rules and instructions for inspection and testing of locomotives, other than steam, and their appurtenances, I.C.C., Dec. 14, 1925, as amended at 24 F.R. 476, Jan. 21, 1959]

Wheels with any of the following defects shall not be continued in service:

(a) Slid flat. Slid flat, when the flat spot is 22 inches or over in length, or if there are two or more adjoining spots each 2 inches or over in length.

(b) Broken flange. Broken or chipped flange, if the chip exceeds 12 inches in length and one-half inch in width.

(c) Broken rim. Broken rim, if the tread, measured from the flange at a point five-eighths inch above the tread, is less than 33⁄4 inches in width.

(d) Shelled out. Wheels with defective treads on account of cracks or shelled-out spots 21⁄2 inches or over, or so numerous as to endanger the safety of the wheel.

(e) Seams. Any seam running lengthwise and within the limit of 33⁄4 inches from flange, as shown in figure 13.

(f) Worn flanges. Wheels with flanges having flat vertical surface extending 1 inch or more from the tread, or flanges fifteen-sixteenths inch thick or less, gauged at a point three-eighths inch above the tread, except cast-iron or cast