Maryland Corrections Commissioner Jon P. Galley today named Wayne B. Winebrenner, assistant commissioner for field services, as acting warden at the Maryland Correctional Institution in Hagerstown. Winebrenner replaces warden James P. Tinney III, whose firing Galley confirmed today.

Galley also confirmed that four guards have been ordered dismissed and four others suspended over the alleged beating of six inmates last October at the state prison complex in Hagerstown. The firings and suspensions were predicted in news accounts last week.

Corrections officers in Hagerstown voted tonight to begin a work slowdown to protest the firings, but a corrections department spokesman said there was no immediate evidence of a slowdown, The Associated Press reported.

Galley would not specify why he removed Tinney except to say he was "not satisfied with his overall performance as a manager of the institution." Other sources said the dissatisfaction involved several aspects of Tinney's administration, including the way he handled the alleged beating incident.

In the incident, six inmates accused guards of beating them while the inmates were shackled. They also contended that white guards ordered black inmates to call them "master."

The guards have denied the allegations. Spokesmen for the Maryland Classified Employes Association, which represents the guards, said the six inmates had been ringleaders in a disturbance at the Maryland Correctional Training Center in Hagerstown and were being transferred across the road to isolation cells in the Maryland Correctional Institution when the incident allegedly occurred.

The guards contend that the inmates provided no evidence of the beatings and that prison authorities did not investigate the incident properly.

Suspension of four of the guards takes effect immediately, authorities said. The four ordered dismissed may first seek a hearing before a state personnel arbitrator, where their dismissals may be upheld or reversed.

Maryland Classified Employes Association officials said they will provide attorneys for guards seeking to halt their dismissals.