他们放下轿子，以一柄铜锤敲了三次门。

They set down the palanquin and knocked three times with a copper hammer.

看到制式锤我有个问题：图中的铜锤是否就是侍卫用的金瓜？

I have a question that whether this copper hammer in pics is the golden hammer used by guard?

老铜锤也有空心的，一般用于仪仗和武馆陈列，往往还是装饰做工精细的，但这对确实是药。

The ancient copper hammer also has empty heart. Generally, it was used for amenity and display of Wushu. And always used for decorating, and its technic is refined.