What does black Sam do when he tries to stall Mr. Haley from taking Tom

Didn't you mean Eliza in Ch. 6? Mrs. Shelby joins in as well, by defying her husband and telling the slaves to "Be careful of the horses; don't ride them too fast." A slave, Sam, understands his mistress' meaning and places a burr under the horse's saddle so that it bolts and throws Haley. It takes several hours to catch the horse, and Sam must first rub it down before Haley can ride it. Thus, the slaves outwitted the slave trader and bought much precious time for Eliza.