race jack problem broken

feel like a idiot
any help appriciated
i got a set of used jacks like projacks but form a generic company
thew rear tires were off the car while working on rearbrakes
i put the rear one under rear of car
and the front under front
then lifted it up it did go up little slow but fine
then i swung over the safteys
i slowlylowered the jack onto the saftey and the rear slamed down and then the front slowly lowered .(thought it was weird )
then i raised it back up removed safteys and atempted to lower car
when i slowly hit the relase SLAM went the back of the car the rear droped to the ground it also borke both himejoints at the ram
now the front is stuck up and wont come down
later to find that the disconnect fitting was keeping the front from relasing

did i do something wrong ????
if i replace all the disconects and hoses and two hime joints
will that solve problem
or maybe jacks arnt strong enough for 2700lb car

thanks chris

 

Whose are these?

 

i was told from england

they are gold anodized

 

put a hydraulic flow control on them so you can control the rate the fluid goes back to the pump

 

So there made of aluminum?

 

Jacks

I agree it they don't have a flow valve add one , most of the time I hear something like this air is the problem, it got air in the line when disconnecting them. that will make them spungy and cause them to move very fast because the air will move so much faster than the oil. I would bleed the system to remove all air and check to see how it got in there

 

made of steel

not aluminum \
very strong steel and heavy

thanks john valve makes sence
also thanks on air in lines also makes sence



any reason on why the hime joints broke ?
was it cause it slamed down to fast ?