Dropdown menu not working on mobile - html

Question

I have searched high and low and tried many different options from here, but i need a point in the right direction now :)
On this site:
http://www.michael-smith-engineers.co.uk
On the main nav, (in mobile view) if you click on Pumps, there should be further dropdown options, but i can not get this working. Any ideas would be appreciated.
I have tried adding the following script, without any luck...
<script>
// see whether device supports touch events (a bit simplistic, but...)
var hasTouch = ("ontouchstart" in window);
var iOS5 = /iPad|iPod|iPhone/.test(navigator.platform) && "matchMedia" in window;
// hook touch events for drop-down menus
// NB: if has touch events, then has standards event handling too
// but we don't want to run this code on iOS5+
if (hasTouch && document.querySelectorAll && !iOS5) {
var i, len, element,
dropdowns = document.querySelectorAll("#nav-site li.children > a");
function menuTouch(event) {
// toggle flag for preventing click for this link
var i, len, noclick = !(this.dataNoclick);
// reset flag on all links
for (i = 0, len = dropdowns.length; i < len; ++i) {
dropdowns[i].dataNoclick = false;
}
// set new flag value and focus on dropdown menu
this.dataNoclick = noclick;
this.focus();
}
function menuClick(event) {
// if click isn't wanted, prevent it
if (this.dataNoclick) {
event.preventDefault();
}
}
for (i = 0, len = dropdowns.length; i < len; ++i) {
element = dropdowns[i];
element.dataNoclick = false;
element.addEventListener("touchstart", menuTouch, false);
element.addEventListener("click", menuClick, false);
}
}
</script>
This script above is ridiculous for what i was trying so, tried this:
<script type="text/javascript">
function is_touch_device() {
return (('ontouchstart' in window) || (navigator.MaxTouchPoints > 0) || (navigator.msMaxTouchPoints > 0));
}
if(is_touch_device()) {
jQuery('.toggle-menu').on('click', function(){
jQuery(this).toggleClass('activate');
jQuery(this).find('ul').slideToggle();
return false;
});
}
</script>
</head>
Still no luck tho?!!!!