PARTIES TO DISPUTE:

STATEMENT OF CLAM "Claim of the System Committee of the Brotherhood that:

 (1) The dismissal of Extra Gang Laborer R. J. Valdez for 'alleged insubordination, intemperance, and carelessness of the safety of himself and others' on July 8, 1980 was arbitrary, capricious, without just and sufficient cause and on the basis of unproven charges (System File D-18-80/NbT-27-80).

 (2) Extra Gang Laborer R. J. Valdez shall now be allowed the benefits prescribed in Agreement Rule 28(d)."

 OPINION OF BOARD: Claimant, Mr. R. J. Valdez, entered service of the Carrier on
 May 7, 1979* and at the time of the alleged incident was working as an extra gang laborer. On July 14, 1980 Claimant received a notice to attend a formal investigation on July 17, 1980 to:

As a result of this investigation Claimant received notice dated July 25, 1980 that he had been found guilty as charged and that he was dismissed from service of the Carrier.

 An analysis of the transcript of the hearing shoes, that according to the testimony of the Extra Gang Foreman, Claimant walked away from the adzing machine he was operating when he was criticized by this Foreman for cutting ties too deeply and for being slow when operating the machine. There is inconsistent testimony from the hearing transcript concerning the sequence of events which followed after this. According to supervisory witnesses Claimant then took off his shin guards and threw them in an intemperate and careless manner, removed his glasses and hard hat, and used gestures and language which were threatening to the Extra Gang Foreman. Co-workers who appeared as witnesses on the other hand, stated that Claimant only uttered (what according to all can only be construed as inappropriate) strong verbal countermands to the Foreman

 *Prior to this Claimant had worked for the Carrier for several months in 1976 (Carrier's Exhibit I).
 Award Number 24311
 Docket Number NW-24244

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 when the Foreman pushed him after the Claimant had taken off his shin guards and "pitched them" on t ground in a manner which proportedly is not uncommon with this type of safety equipment.
 This Board has gone on record on many occasions to the effect that it is not constituted to make determinations related to conflicting evidence (See Third Division Awards 23085 and 22145, inter alia ). In this respect, this Board quotes Award 22721, which states: "issues of credibility must be determined by those who received the evidence and testimony, and (this Board) (has) ... no basis for substituting (its) judgment in that regard".
 Upon review of the record,.therefore, this Board finds no factual basis for reversing the determination of the Carrier in this matter.

'that the parties waived oral hearing;

 That the Carrier and the Employes involved in this dispute are respectively Carrier and Employes within the meaning of the Railway labor Act, as approved June 21, 1934;
 That this Division of the Adjustment Board has jurisdiction over the dispute involved herein; and

 That the Agreement was not violated.

 Clai m denied.

 Attest: Acting Executive Secretary
By ,1C/C/~Gt~
 Rosemarie Brasch - Administrative Assistant Q CE I V E p

 ~ , _

 Ch/.
 ago Offices

 Chica Illinois this 14th da of Aril 18.

 NATIONAL RAILROAD ADJUSTMENT
BOARD
 By Order of Third Division

 Dated atgo,,yp93