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Subchapter 6. Elevator Safety Orders
Article 8. Machinery and Equipment for Power Cable-Driven Passenger and Freight Elevators

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§3031. Car and Counterweight Buffers and Bumpers.

(a) Type Required.

(1) Buffers or bumpers shall be installed under the cars and counterweights of all cable-driven power elevators.

EXCEPTION: Counterweights of existing elevators which have never had bumpers or buffers.

(2) Spring buffers, oil buffers, or their equivalent, shall be used on all cable-driven power elevators.

EXCEPTION: Solid bumpers of rubber, wood, or other material having similar shock absorbing qualities may be used on:

1. Existing installations of solid bumpers.

2. Existing elevators having a rated speed of 50 feet per minute or less which have never had bumpers.

(3) Oil buffers or their equivalent shall be used where the rated speed is in excess of 200 feet per minute.

EXCEPTIONS:

1. Installations of bumpers or spring buffers made before June 5, 1947.

2. Where Type C safeties are used, solid bumpers may be used under the car.

(b) Location.

(1) Buffer or bumpers shall be located symmetrically with reference to the vertical centerline of the car frame or the counterweight frame, within the tolerance of 2 inches. The car bumpers or buffers shall be located so that the bottom runby does not exceed 24 inches.

(2) Buffers or bumpers shall be located in the pit.

EXCEPTIONS:

1. Oil buffers mounted on the counterweight.

2. Existing buffers mounted under the car.

(c) Stroke of Spring Buffers. Spring buffers shall be constructed so that the stroke of the buffer spring, as marked on its marking plate, shall be equal to or greater than the following:


Rated Car Speed                                   Stroke 
Feet Per Minute                                   In Inches 
100 or less....................................... 1 1/2 
101 to 150........................................ 2 1/2 
151 to 200........................................ 4 

(1) The spring buffer shall be mounted so that the spring will be compressed solid before the car or counterweight rests on the buffer support.

(d) Load Rating of Spring Buffers. Spring buffers for cars and counterweights shall:

(1) Be capable of supporting, without being compressed solid, a static load having a minimum of twice the total weight of:

(A) The car and its rated load for car buffers.

(B) The counterweight for counterweight buffers.

(2) Be compressed solid with a static load of 3 times the weight of:

(A) The car and its rated load for car buffers.

(B) The counterweight for counterweight buffers.

EXCEPTION: When Section 3019(a)(2) necessitates a greater load rating.

(e) Marking Plate for Spring Buffers. Each spring buffer shall have permanently attached to it a metal plate marked in a legible and permanent manner to show its stroke and load rating. (The load rating is the load required to compress the spring an amount equal to its stroke.)

(f) Stroke of Oil Buffers. The minimum stroke of oil buffers shall be based on the requirements outlined in Design Section 3108(a). Table 3031 F indicated the minimum buffer strokes for the most usual rated speeds.

EXCEPTION: When oil buffers are used in conjunction with an emergency terminal stopping device conforming to the requirements of Section 3039(c) which will limit the speed at which the car or counterweight can strike its buffer the following shall apply:

1. Reduce stroke oil buffers may be used on modernization installations in existing hoistways provided that the stroke of the buffer shall be as long as possible for the existing conditions.

2. Reduced stroke oil buffers may be used for new installations when installed as follows: The buffer stroke shall be based on at least 115% of such reduced striking speed on an average retardation not exceeding 32.2 ft/s2 (9.81 m/s2). In no case, shall the stroke used be less than 50% of the stroke required by Section 3031(f) for rated speeds under 800 fpm (4.06 m/s), nor less than 33-1/3% or 18 inch (457 mm), whichever is greater, for rated speeds of 800 fpm (4.06 m/s) or more.

NOTE: See Section 3031(m). Testing of Oil Buffers.



                       TABLE NO. 3031F 
                    Minimum Buffer Strokes 

                      115% of                     Minimum Strokes 
Rated Speed In     Rated Speed in                 of Oil Buffers 
Feet Per Minute    Feet Per Minute                   In Inches 
   200................. 230                           2 3/4 
   225................. 259                           3 1/4 
   250................. 288                           4 1/4 
   300................. 345                           6 1/4 
   350................. 402                           8 1/4 
   400................. 460                          11 
   450................. 517                          13 3/4 
   500................. 575                          17 
   600................. 690                          24 3/4 
   700................. 805                          33 1/4 
   800................. 920                          43 3/4 
   900................ 1035                          55 1/2 
  1000................ 1150                          68 1/2 
  1100................ 1265                          83 
  1200................ 1380                          98 1/2 
  1300................ 1495                         115 1/2 
  1400................ 1610                         134 1/2 
  1500................ 1725                         154 
  1600................ 1840                         175 1/4 
  1700................ 1955                         197 3/4 
  1800................ 2070                         221 3/4 
  1900................ 2105                         247 
  2000................ 2300                         273 3/4 

* Where buffers of the stroke specified are not provided, the requirements of Section 3031(f) exceptions apply.

GENERAL NOTE:1 fpm=5.08 E-03 m/s1 in.=25.4 mm

(g) Retardation by Oil Buffers. Buffer retardation rates shall conform to the requirements of Design Section 3108(b).

(h) Factor of Safety for Oil Buffer Parts. The factor of safety of oil buffer parts shall conform to the requirements of Design Section 3108(c).

(i) L/R for Members Under Compression as Columns. The L/R ratio for oil buffer members shall conform to Design Section 3108(d).

(j) Plunger Return Requirements. Oil buffers shall be so designed that:

1. The buffer plunger of the gravity-return and spring-return type oil buffers, when the buffer is filled with oil, shall, when released after full compression, return to its fully extended position within 90 seconds.

2. The plunger of a spring-return type oil buffer with a 50 pound weight resting on it shall, when released after being compressed 2 inches, return to the fully extended position within 30 seconds.

3. Car and counterweight buffers of the spring-return type shall be provided with a switch, operated by the buffer in case it is compressed more than 3 inches, and so connected to the control circuit that the speed of the descending car or counterweight shall not exceed 1/2 the rated speed unless the buffer plunger returns to within 3 inches of its normal position.

EXCEPTION: Elevators with buffers installed before June 5, 1947.

(k) Means for Determining Oil Level. Oil buffers shall be provided with means for determining the oil level, and that the level is within the maximum and minimum allowable limits. Glass sight gages shall not be used.

(l) Approval of Oil Buffers. Every type oil buffer shall be approved by the Division of Industrial Safety before installation. The approval shall be based on tests witnessed by a representative of the division, or certified test reports as specified in Design Section 3108(g) may be accepted.

(m) Testing of Oil Buffers. On each installation of an elevator equipped with oil buffers, a field test of the buffers shall be made, and witnessed by a representative of the division, consisting of running the car with rated load onto its buffer at rated speed and the counterweight onto its buffer at rated speed with the car empty. In making these tests, the normal terminal limit switches shall be made temporarily inoperative, and the final terminal limits shall remain operative but shall be temporarily relocated if necessary to permit full compression of the buffer during the tests.

EXCEPTION: (Section 3031(m))

Reduced stroke buffers shall be struck at speeds reduced to conform to the stroke of the buffer used, and the test shall demonstrate that no part of the car or counterweight will contact the overhead structure. Failure to so demonstrate shall require adjustments or modifications acceptable to the division.

(n) Load Ratings of Oil Buffers. The minimum and maximum load ratings of car and counterweight oil buffers as indicated on the buffer marking plate shall conform to the following:

1. The minimum load rating shall be not greater than:

(A) For car oil buffers, the total weight of the car as marked on the crosshead data plate plus 150 pounds.

(B) For counterweight oil buffers, the weight of the counterweight used.

2. The maximum load rating shall be not less than:

(A) For car oil buffers, the total weight of the car as marked on the crosshead data plate plus the rated load.

(B) For counterweight oil buffers, the weight of the counterweight used.

(o) Oil Buffer Marking Plate. Every installed oil buffer shall have securely attached thereto a metal plate, marked by the manufacturer in a legible and permanent manner, indicating:

1. The maximum and minimum loads and the maximum striking speed for which the buffer has been approved.

2. The manufacturer's identifying type or number of the buffer.

3. The permissible range in viscosity of the buffer oil to be used, stated in Saybolt Seconds Universal at 100 F.

4. The viscosity index number of the oil to be used.

5. The pour point in degrees F. of the oil to be used.

6. The stroke.

NOTE: Authority and reference cited: Section 142.3, Labor Code.

HISTORY

1. Amendment of subsection (f), Table No. 3031 F and subsection (m) filed 5-12-83; effective thirtieth day thereafter (Register 83, No. 20). Approved by State Building Standards Commission 4-4-83.

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