How heavy are the Boeing 747 landing gear?
It seems I misspoke in my comment in which I gave the moments for 747-400BCF gear retraction. I didn't realize the component weights were further on in the document I referenced. The weights for the BCF are:

body gear 6447 lbs (2924 kg) each

wing gear 6508 lbs (2952 kg) each

nose gear 3157 lbs (1432 kg)

However, @Gurkan's comment is relevant in that you have to decide what all should be considered as part of the gear. So, I put up a PDF of the WEIGHT AND BALANCE CONTROL AND LOADING MANUAL for each of two 747 freighter variants. You can access them at terryliittschwager.com/wbmanuals.php. The most relevant sections are 1-86-041 and 051.